Troubleshooting Low Oil pressure

Oil. It’s quite important stuff in engines, especially in aeroplane engines. Considering the only thing keeping us up in the air is the engine it makes sense to keep a close eye on the oil.

He who is without oil, shall throw the first rod

Compressions 8.7:1

I have an issue with a low oil pressure reading. It would be less irritating if there was some oil floating around in the cowling, or a stripe down the fuselage, but no. Not a drop.

Initially it seemed like the pressure dropped with altitude which made us suspect that there may be an issue with the breather pipe, but the oil system on the Rotax is somewhat more complex than the wet sump on most aviation pistons. The engine is a dry sump system. The oil resides in the oil tank (perhaps unsurprisingly) and is pumped from there to the oil filter via the oil cooler by the oil pump which is driven by the camshaft. Oil returning to the sump is pumped back to the oil tank by blow by gases, the Turbocharger has oil pumped via a secondary line and the oil drains from the turbo sump to the oil tank.

The oil pressure is measured by a sensor ‘distal’ to the pump and there is a pressure regulator. The pressure regulator may be the source of the issue – it contains a spring and a ball bearing which regulates the pressure. When we looked at the engine analysis graphs again it appears that there is a better correlation between oil pressure and oil temperature, rather than altitude.

Oil pressure in blue plotted against oil temp (Purple ) and Altitude (green/yellow)

This may mean the problem is easier to solve. Maybe. As temperature increases the viscosity of oil decreases – which may make it harder to pressurize if there is some issue with the seal, pump, oil cooler bypass etc etc.

What this really needs is someone with real know-how to test fly the aircraft, possibly also inserting a mechanical Bourdon tube type gauge into the system and comparing pressure readings. What I wanted to do was to try and replicate the problem with the altitude factor removed – and this would mean flying in the pattern at high power until the oil temperature rose enough to decrease the oil pressure.

So this is what I planned to do. Of course, having an issue to solve on the aircraft almost certainly means that no time will be available to fly so it is 10 days later and time to test fly. That was the plan anyway. Of course, on arrival at the airfield I found it blanketed in mist despite the late hour (9:30am). Not a problem, I had another job to do and that was to try and get a fuel stick calibrated.

I had a great idea for this job – take a hose pipe, stick it into the tanks, siphon out as much as I could then sump the rest out. Well, that plan did not work at all. Firstly I could only siphon 25 litres from the tanks before the hose was uncovered and I couldn’t push it further into the tank (admittedly, I was loathe to force it in in case it did damage to the float gauge). Also, siphoning petrol is no fun at all. I got quite a lot of fuel in my mouth and in my nose which caused me to smell like I was living in a fuel tank for the rest of the day.

I decided to compromise and drain until the area directly below the filler port was dry ( ‘to tabs’ if you will) and then measure how much fuel it would take to fill the tanks to the brim again. With a known tank capacity (84 litres) I could subtract this amount and have the fuel level at tabs. As it turns out, if the tabs are dry, there is less than 35litres in the tank. Good to know. I like having some kind of scientific estimation of fuel tank volume. I used a big piece of wood, marked it as I filled the tank 12.5 litres at a time and then transferred these marks onto a wooden dowel stick.

Primitive Dipstick

While I was sorting this out, the fog had lifted to low overcast but that seemed compatible with circuit flying so I started up and headed out. On climbing out from the field I couldn’t help but notice the rather large storm approaching about 30km away – this was going to put a spanner in the works. Still, I was able to do about 5 circuits at high throttle settings, getting the oil temp up to 82 Celsius / 180 Fahrenheit- without causing a low oil pressure alarm – the pressure did decrease though – as shown in the Savvy graph below.

Top graph is Oil Temp against Pressure – seems to correlate somewhat doesn’t it?

The incoming storm put paid to the 30min flight I was hoping for and I put her down very quickly – into the teeth of the Cb outflow – not my best ADM moment but safely down and we crammed the plane into the hangar just as the first drops were starting to fall.

It looked worse than this in real life!

There will be no flying for the next two weeks but after that I’m popping IBM across to the AMO for the oil change and they will check and possibly change the oil pressure regulator – which will hopefully sort out the issues. To be honest I think it needs a climb to altitude and thereafter a throttle back to allow oil Temp to decrease a bit to fully troubleshoot. Time will tell. In the meantime, I need to wash my hands. Again. Blood petrol….

That Sling Smile

Yesterday I was fortunate enough to be able to take my friend Ari flying. He may not know it but he’s actually my aviation mentor – one heck of a nice guy who has a knack of thinking about general aviation in ways I haven’t thought of. He’s a commercial instrument rated pilot with more than 1500h and he flies a FIKI Cirrus SR22T with his father.

One reason we are buddies is that we have similar outlooks on general aviation safety and doing GA correctly. My feelings on these are borne out of lots of reading – his I suspect are from lessons learned in years of flying. It can be daunting flying with a significantly more experienced pilot in a non instructor/examiner situation (OK, it can be very daunting flying with an examiner) because one feels like one’s skills are on show – this was the first time I was to be PIC in my aircraft with him (I’ve flown in his aircraft many times). You don’t want your first flight with a new passenger to be your last flight with that passenger..

Special Sling preflight pose – lifting the elevators to view the control rod attachment bolt

I must confess to feeling that the Sling was a little shabby compared to the extremely well equipped G5 Cirrus but hey, an airplane is still an airplane – and I’m a proud owner.

We had a secondary objective and that was to test the Aerox system I acquired recently – it seemed prudent to do this with an experienced supplemental oxygen user. We came prepared – he had 2 oximeters and I had 1. Of course, true to form mine was DOA, although after 10years of hard use in my day job meant I shouldn’t be surprised. It is time for a new one anyway as the LCD display isn’t very readable in the bright cockpit. In addition we had an emergency cylinder in case the main cylinder didn’t perform as expected.

For a change the weather was playing along really nicely and although the visibility wasn’t really good, the air was smooth as we climbed energetically away from BaraG – had a good 750-800fpm climb rate which impressed my passenger. There was no other traffic in the training area and we started our climb after exiting from under the Johannesburg TMA. Information approved our climb and handed us over to the area controller (Centre) and I handed control over to Ari. For the last day in March it was still pretty warm – was showing an OAT of 21 Celsius at 10000ft but the Sling trundled on at 400fpm through 11000ft with the Airmaster Prop in Climb and 34” manifold pressure on the throttle.

We routed south as we climbed, out over the Vaal River and Parys, enjoying the views (despite the limited vis) and the smooth air. Climbing through 10000 feet I popped the pulse oximeter on and was quite alarmed to find my sats were 89%. I wasn’t expecting it to have dropped so low at a relatively low altitude. I didn’t feel any adverse effects although I don’t believe time of useful consciousness is an issue at this altitude. However, it seemed like a good idea to get the oxygen on which we did.

Looking silly with a poorly applied Oxysaver

Let it be said that one looks a little ridiculous wearing an oxysaver cannula – but you look a lot less ridiculous with the cannula on than slumped over the controls with two fighter jets on your wing. The oxysaver allows pretty low flows – <1litre per minute at altitude up to 15000ft – by using a small reservoir so it’s relatively economical to run once you’ve forgotten the initial outlay for the equipment!

Above the inversion @11500ft south of the Vaal River

Area control came on asking us to stop our climb at FL125 due to other traffic on the airway above us which was a little disappointing but the density altitude was already well over 14000ft by this time, so I didn’t think with a service ceiling of 16000ft we’d get much higher anyway.

Heading back into the smog…

At this point we noticed that the oil pressure had decreased to 1.6bar from 2.5bar. Lower limit of normal is 2bar on the Rotax 914UL. This was obviously not something to take lightly. Initially we thought it could have been due to the warm conditions – oil temp was normal and CHT’s were within limits. Still, we arrested the climb and throttled back with no improvement. The best call at this point was a 180deg turn and route back to home base keeping a good lookout for potential off airport landing sites.

We had to descend to avoid busting airspace and as we descended below 9500ft the oil pressure recovered to normal and stayed there, going up to 3bar as we leveled off at 7000ft. Given that there was no other indication of abnormality we felt it was reasonable to do some maneuvering while keeping an eagle eye on the engine gauges.

I did two steep turns (PPL standard @ 45deg) and thereafter Ari did 2 at CPL standard (60deg). That man can fly an airplane – made the wake on the second attempt in an unfamiliar aircraft. He was raving about the control responsiveness and the inherent balance of the Sling – I think he was quite impressed – high praise indeed from someone who has hundreds of Cirrus hours. “It feels like I have an RV Grin,” he said as we cruised back for the overhead at Baragwanath. I dubbed it the “Sling Smile”

Steep turns – fun!

One touch and go then a full stop landing and it was time to put the plane away. I did get some constructive criticism of my crosswind landing – I need to try and land upwind of the centreline rather than ON the centreline – this makes sense as it gives one a few more metres to deal with any squirrelly behaviour after touchdown.

All in all a successful morning’s flying. The oil pressure reading remains a concern but I’m waiting on the AMO to comment. We suspect it may be a grounding issue or a problem with the oil breather pipe. We had a good look around the inside of the cowling and there is absolutely no oil leaking anywhere and no oil stain on the belly of the plane. Time will tell – the joys of aircraft ownership…

Weather 1 – Me 0

I was supposed to fly to Middelburg(FAMB) this afternoon to camp at the AeroClub of SA Airweek being held there this weekend. The weather, it seems, had other ideas.

I was delayed by 30min at work this morning and by the time I arrived at the airfield the storm line was developing. I hung around finding things to do on the plane until 16h00 local by which stage I could probably have found a route but the flying time would have meant an after dark arrival – and I’m not night current at the moment – not landing at an unfamiliar field at night thank you very much.

The proposed route – see the problem?
Waiting for the rain to stop….
Shortly after deciding to NOT fly to MID…

Tomorrow is another day……

Obsessive Radar checking – a trip to Zebula

My brother-in-law’s family have a place in a game reserve called Zebula – we have driven up with them a couple of times before for the weekend – the house is great with a pool and a jacuzzi and it is good to hang out with family. The reserve has an airstrip which is well frequented with breakfast runners – the lodge will pick you up from the airstrip, deliver you to the buffet breakfast and return you later to your waiting aircraft.

Every time we have been before I’ve looked at the airstrip and thought – “this would be a great fly-in spot.” The strip has a bit of a reputation for being difficult – mostly because it gets very hot in the Limpopo Bushveld and the gradient on the airstrip almost requires a one-way in, one way out philosophy.

On Friday my sister suggested that we fly in and join them for the day on Saturday or Sunday, so we rustled up some cold meats and drinks and I started to have a close look at the trip. Zebula has a 1400m/4500ft , 13metre wide runway which is at 4300ft elevation and slopes fairly steeply from the midway point of runway 08 to the threshold of runway 26. My major concern was density altitude – I knew we’d get in just fine but it was the flying out that had me concerned – more on that later.

Of course, having a trip planned for a Saturday morning was bound to annoy the weather gods and Saturday dawned with a 400-600foot overcast; OK, it was reported as BKN but to all intents and purposes it was overcast. Very occasionally there was a slight break in the cloud and I could see it wasn’t very thick – so we were almost tempted to try and blast through it. This would have been a mistake. After making hourly determinations I decided it was best to delay for 24h. Which, as it turned out, was very much the correct decision. Sunday was clear and the flight was on.

Routing – FASY – Zebula

Baragwanath to Zebula is a leisurely 105nm – of course cannot be flown straight line as there are TMA’s to be avoided. We loaded the cooler bags, swimming kit and ourselves and set off. Today I was expecting the slightly longer takeoff run but IBM shot up enthusiastically and it was sad to have to stop the climb at 7500ft. We cruised over the west of Soweto, over Orient Glider airfield (where not even one glider was out of a hangar yet) and then through the Magaliesberg flight training area – where I did the majority of my PPL training. Entering the GFA, we were out from under the TMA so we climbed up to FL95, above the scattered cumulus which was starting to develop and into some cool, smooth air.

Clouds below
Yes – there is precious little in the way of horizon here

30 minutes later we were top of descent for Zebula – the windsock was essentially indicating mostly crosswind with a slight tailwind component – I elected to land with the mild tailwind to make use of the uphill slope. Unfortunately we floated quite a bit on roundout and I ended up landing at the top of the hill (with plenty of room to spare) – I think the wind shifted a bit more towards the tailwind – as we were securing the aircraft someone landed a 182 downhill into the wind. The tailwind component could not have been more than 5knots and my MAUW landing roll is 400m so yes, I had some wiggle room.

Cool.
Wrapped up for the day – Zebula – YAK 18T on the left!

As we arrived at the lodge, some cumulus was starting to develop – one large one in particular to the north of us. I called up the weather radar feed – sure enough this was developing into something. I spent the rest of the morning checking the feed every 30min to keep an eye. At the mercy of the weather, with no ability to stay late if need be, it is important to keep a close watch. Unfortunately having to worry about the weather does detract somewhat from the relaxation aspect of a morning in the bush – I would be more relaxed if it wasn’t the whole family.

Fortunately, the weather didn’t develop into anything more than clear sky cumulus. When time came to leave the bases were at FL100 with 4/8 cover. Leaving Zebula presented a bit of a quandary. The wind had shifted so it was now aligned with the runway. The uphill runway. Additionally my daughter decided she wanted to sit up front so I needed to do a quick recalculation of the weight and balance – which still came in within the envelope. The wind was of sufficient strength that I didn’t believe I could justify a downwind takeoff – especially with an air temp of 36 Celsius and a calculated DA of over 8000ft.

The Sling will clear a 50ft obstacle at MAUW at 7500ft DA in 690m so I reckoned if we added 10% for the elevated DA and another 20% for the slope we would be clear of 50ft obstacle (the trees at the end of the runway) in 900m, well short of the 1400m available. The wind was about 10kts which would give us back another 5% so in my mind we’d be fine. In fact, we lifted off marginally short of halfway (just at the top of the sloping section) and climbed strongly at Vx to the extent that I was turning on course as we passed the far threshold. I’m continually amazed by the takeoff perfomance delivered by the little Rotax 914.

Clouds above
Approaching the Magaliesberg Northern Ridge

I had hoped to climb to FL105 or FL125 for the trip home to get some cool air but the cloud bases were around FL100 so we stayed at FL85 – which was a lot bumpier than the family have experienced – precipitating some nausea on the part of one member. Again we routed over the glider airfield (OK, about 3miles to the west thereof) – it is lovely to see the gliders below and the guys launching with the winch.

North of Brits
Engrossed in her iThing

Landing at Bara was very enjoyable – with the very rear C/G we did a wheelie for ages after the mains touched down – there is incredible elevator authority down as far as about 38kts – in fact on a proper short field takeoff the nose will unstick at 40kts.

The “Concrete Tower” – an important VFR reporting point in the Magaliesberg General FLying Area

Another new airport into the logbook, another family trip living the Sling lifestyle. The only negative aspect is that the pitch part of the autopilot is STILL not working properly, which is proving to be somewhat annoying. I need to look at that again this week.

The next trip is to Middelburg (FAMB) for the EAA aviation week. Can’t wait.

Breakfast in Parys

To say that the year thus far has not been great for flying is no understatement. As soon as MGL Avionics opened this year I sent my EFiS in for hardware upgrade and that took 2 weeks – where I (obviously couldn’t fly). As that came back and it was re-installed, the wet season arrived with a bang. We’ve been laboring under a ridge of high pressure which has been driving warm moist air from the Mozambique Channel down over Gauteng with resultant overcast and showers. In fact we had about 3 weeks of continual 7/8 to OVC (mostly on the weekends). However, the first signs of the late summer/early autumn period are starting and we’ve had a week or so of fantastic flying weather.

We thought we’d take advantage of this and do the “Sunday fly out to breakfast” thing. This was to be the first time we’d all gone flying as a family and would be a good test of IBM’s load carrying capacity. It should be noted that she’s no Cherokee 235 but with a useful load of 465kg four up is definitely a viable option.

Sunday dawned clear despite the forecast high overcast, so we loaded up and set off for the airfield. The preflight was accomplished fairly quickly thanks to my two helpers who are getting quite good at removing the plugs, covers and the 40kg of water ballast I keep in the rear when flying solo. After the obligatory fiddle with the goPro’s we were able to start up.

PreFlight assistance?
DateAircraftRoute of FlightHoursTotal Hours
24 Feb 2019ZU-IBMFASY(Baragwanath) – GAV –
FAPY(Parys, FS) GAV – FASY
1.4126.4

There was a fair amount of activity on the field as we taxied out – someone was preflighting a Samba XL, my neighbor across the taxiway was (still) fighting with the autopilot in his Jabiru and someone was doing circuits in a Robin. For only the second time since I moved to BaraG winds were favoring runway 13 and we launched without issue. I expected a significantly longer takeoff roll being four up but it wasn’t a big issue – what did get my attention was the slower climb performance – my usual stick deflection produced a Vx climb at 65KIAS as opposed to the more routine 75KIAS but there is a ridge to the south of the airfield which needs to be crossed….

Hard to get this one wrong – straight lines for the win!
4 up in the Sling

Having negotiated the ridge we made a leisurely climb to 7000ft, progressed through the surprisingly quiet GF and made our way to Parys. There are only about 20nm between the edge of the Special Rules Area (7000ft southbound) and Parys, but we needed an even flight level – and for reasons best known to myself, I asked Info South for FL85 which meant that 2min after reaching, I was asking for descent. (It would have been more clever to ask for FL065

Crossing the Vaal into the Free State – FL085

Parys was busy with a Baron back taxiing and two gyros inbound. I performed a textbook unmanned join, with an extended downwind to allow the Baron to depart and landed with the two gyrocopters hot on my heels. Then we had a humorous moment where the only taxiway off the runway was blocked by an aircraft taxiing out – this required some negotiation but fortunately we are all nice folks…

Miss Daisy resting at temporary parking
Montgolfier’s Restaurant – Parys Airfield (FAPY)
There is always time for more photos….

The restaurant at Parys has recently been put under new management and is now called Montgolfier’s. It’s very relaxed, cool and comfortable with a great view of the temporary parking and runway. Food is reasonably priced and tasty, service is as quick as you’d expect for a leisurely Sunday breakfast – all in all a great experience.

Cessna C185 ZS-PHT
PA28-235 (Cherokee) – ZS-DVG

As we started up to head home, the gliders were being pulled out, so we weren’t too surprised that it was a little bumpy – nothing unmanageable of course, but the thermals were starting up. Back at BaraG we landed uneventfully again on RWY 13 (The Sling LOVES a rear CG for landing – #Wheeliesfordays!).

For a first time family trip, it was great – and the rear seat passengers remarked that they’d be prepared to spend more time back there..

Taking Miss Daisy to Springs

I have been looking for an opportunity to take some family members flying in ZU-IBM. There is a heck of a lot going on at the moment with year end functions, prize-givings, concerts and the like and there simply isn’t a lot of time. When the Springs airport fly-in came up though we decided to make a morning of it. Some family members preferred their beds to an early flight so it was only myself and my son braving the trip to the East Rand. 

I tend to overthink trips to unfamiliar airspace. I’ve only been east of OR Tambo Johannesburg International Airport (FAOR) once and that was a long way wide of the airspace doing my night Nav exercise – this route would call for a very close skirting of the airspace around this large international airport. 

Undaunted though we planned to route from Tedderfield to Springs via Suikerbosrand Nature reserve (incidentally I have not been there since I was about 12y old) – I thought it would give me a chance to do some radial intercepts onto the HGV VOR using the “virtual VOR” feature on my MGL iEFIS – it creates radials based on the GPS position, so one can navigate using VORs without having a Nav radio per se (this will have to be fixed if I’m ever going to use this aircraft for IFR though)

Routing from Tedderfield to Springs giving the Buffer zone a wide berth

Saturday morning’s weather was fairly typical for a Saturday morning at this time of year – beautiful at 04h45, and overcast by 06h30. Fortunately the stuff was thin, was clearing from the east (good news since this was the direction of flight) and it looked like a good day to commit aviation. 

DateAircraftRouteDistanceTime(hrs)Total(hrs)
24 November 2018ZU-IBM
(SLG4)
FATA –
FASI
38nm0.7113.7

I try to involve my kids in the preflight process as I think that the more eyes there are scanning the aircraft, the greater the chance of picking up something – but we both had to stop and gawk as a flight of 4 motor gliders taxied past and departed to Springs – they’re quite elegant and looked like they had some pretty impressive initial climb performance. 

In Cruise Selfie 

Then it was time to set sail – in the video below one can see the smile on my son’s face as we accelerated down Runway 29. The routing was easier than I imagined it would be – and much quicker too – by road Springs is a good 90min drive – took us about 24min all told.  Being total newbies to the fly-in scene we were impressed by the number of aircraft joining the pattern from all directions – generally professional piloting meant that we were able to build some good situational awareness and no surprises appeared (apart from the unexpectedly strong crosswind on the downwind leg)!

There is a bit of pressure landing at a busy field when you know everyone is watching your landing – fortunately we didn’t need a broom to taxi the aircraft off the runway so we retained some credibility. Which I lost for us by asking where we could park…. “Um… in any open spot?” So we pulled up next to a very pretty RV8 (ZU-RVA) and shut down. 

Scott with IBM on the flight line at Springs – Check out that sexy RV8…

Then it was time to wander around and have a look at the aircraft – there was a good representation of general aviation in SA – everything from a Trike to a Cherokee 140, to C210 on the type certified side and lots of Vans Aircraft (Mostly RV7A’s with a spattering of RV-6/a’s and two RV-10’s – not to forget the aforementioned RV-8), A couple of Slings, Jabirus and some Kitfox aircraft on the NTCA side. A Robbie R44 and an Alo II kept the motor gliders company too. 

ZS-CNY Cessna C210
Polaris LSA
FASI_ZULSA_241118
“Sport” cruiser

FASI_ZUMTB_241118
Vans Aircraft RV-10 ZU-MTB 
FASI_ZSOZI_241118
Citabria ZS-OZI

Sadly we were not taking part in the navigation rally and we didn’t have time to stay and watch the departing traffic so it was back to Tedderfield for us.

DateAircraftRouteDistanceTimeTotal
24 November 2018ZU-IBM 
(SLG4)
FASI – FASY
– FATA
551114.7

We wanted to stay well clear of the busy corridor between springs and Rand Airport so I decided to head south until passing over Heidelberg airport and then route for Baragwanath (FASY) airport – which is to be the new home of ZU-IBM for a touch and go before returning to Tedderfield. 

As we were doing run ups at the hold for RWY 03 at Springs there was some commotion on the airport frequency – apparently one of the motor gliders based at Springs had had an engine problem on departure from the grass runway and had completed a safe off field landing – I guess this is bread-and-butter stuff for glider pilots?

We had an uneventful trip back to Tedderfield- did one (average) touch and go at BaraG and then perhaps my best landing to date in the Sling at Tedderfield. I discovered an unexpected advantage of having my son with me – he could hop out and open the hangar, avoiding a shut down and hot start ! – Kids have their uses sometimes… 

We’ll be looking for more fly-ins to attend in future.

Home – Morningstar to Tedderfield – not so simple

All good things must come to an end and this includes congresses – well, OK, being at a congress (even one dedicated to anaesthetising small people) is not as good as not being at a congress when in Cape Town, but it was still worthwhile. 

There was  a huge amount going on from a social point of view but was able to have dinner with an old friend and her family and also to have the most expensive cocktails I have ever drunk – I know it’s Cape Town but R130 for a Mojito is somewhat excessive – it is one of the trendiest spots in town though and the views and architecture made up for the cost of the drinks (almost!)

Arty Mojito shot

I’d deliberately left an extra day to get back – my plan was, if the weather looked at all dubious on the Monday, I’d aim to fly halfway back on Sunday afternoon, use the night rating to land late in Bloemfontein and sleep over and hop home on the Monday. My weather guy seemed confident that weather would be excellent on the Monday – with the proviso I left early ( 0600 local). This seemed to me like an excellent plan – despite the logistical problems of accessing the airfield at that time (beyond the scope of this piece). 

I was surprised to wake up to a thin layer of cloud, which got thicker as I descended down from Rondebosch to the peninsula and headed north to Morningstar. The logistical issues of accessing the airfield at 06h00 were left by the wayside as conditions were low IMC with 1000m visibility but, annoyingly the clouds would break up every few minutes to reveal that the layer was temptingly thin. I could feel the get-home-itis starting to build. It would be very easy to blast through a hole in the clouds, but what if I needed to return? I doubted I’d be able to find the field again, so in consultation with the weather briefer we decided to wait 2hours. This allowed ample time for a very thorough preflight, at least 2 pre departure visits to the bathroom and sorting out returning the hired car to the AMO/FBO. 

Ready and waiting for clear skies

At 8h30 there was much more blue sky than low cloud and I decided the time was now. I taxied out, did my run up and launched off of 02. Climbing through 300ft the EGTs all climbed rapidly through 1100deg – well into the red. It took me about 3 seconds to decide that I was not continuing with this – reported returning to the circuit and got IBM onto the ground as soon and as safely as I could – I will confess that my circuit was not textbook but I was keeping it tight in case the engine quit. Bizarrely the power output felt ok and there was no roughness at all. 

I had the AMO check it out – they ground ran it, and then we test flew the plane again – we were unable to replicate the problem. A possible theory was carburettor icing  (there is no carb heat on the Sling and conditions were favourable for development of carb ice) but there was no discernible power loss so I’m sceptical of that. Another theory is that I didn’t put the mags completely back to BOTH but again, I don’t believe this and once again no issue with power. So I’m at a loss as to what happened, but there have been no abnormal indications since then.

Date of FlightAircraftRouteDistance (nm)Time(hrs)Total(hrs)
12 November 2018ZU-IBM (SLG4)Morningstar to FATA(Tedderfield)6605.9113.0

The nett result of all of this is that it was 10h15 local when I departed, a good 4 hours later than I had wanted. I was hoping for a smoother ride than coming down but was to be disappointed. Initially the air was fantastic and I was settling in for an easy trip but as I approached Sutherland the thermal activity started with a vengeance, as it had on the trip down. I climbed to FL95, where the density altitude was 12750ft – I didn’t believe I could justify a climb to FL115 without supplemental oxygen, so I was properly stuck. 

about to set course inland

It may be something I need to get used to and there may well be a technique to riding the thermals to get maximum efficiency. I think it may be easier in an aircraft that cruises below Va – the Sling will easily cruise in the yellow band – I was having episodes where I was 5-7.5deg nose down, climbing at 700fpm and rapidly approaching Vne, so I would pull throttle to idle, ride out the thermal and then try to time reapplication of throttle to not end up on the back side of the power curve – occasionally I needed to put the prop into climb and once had to put the throttle though the ‘gate’ to 115% power to not sink. This suggested to me that I was not only contending with updrafts but downdrafts as well. 

Not as calm as it looks – crossing the Orange river near Kimberley

This continued for the rest of the trip – to say it was tiring is an understatement. I was again fortunate to be cleared through the Kimberly (FAKM) TMA which cut about 30miles off the trip. Most worryingly for me and the primary reason why I chose not to stop and take a break was the possibility of thunderstorm development. I was overhead Kimberley at about 13h45 local and had planned to already be in my car driving home from the airport by that stage. 

Looking at the radar download I could see that there were some cells starting up so I elected to continue. Approaching Potchefstroom there were definitely cells but they were isolated so was able to manoeuvre my way around them – it is so tempting to fly underneath them but there was a lot of Virga about and I know well that that implies severe downdrafts – best avoided. So we picked our way through the cells. Typically I was unable to raise any cell signal to download the current radar pictures – man I wish we had a decent ADS-B in solution provided here. ATC was fairly noncommittal, “yes there are some buildups but they don’t look too hectic” – easy to say sitting in a comfortable chair. 

Skirting thunderstorms near Potchefstroom

Finally I was able to call overhead Tedderfield – had a bit of a fiddly landing as the gusts were starting up prior to a storm arriving but safely down and then the big job of unloading the aircraft. 

5.9hours in a single leg is a long flight – it would have been better with less turbulence. I learned some important lessons though – leave as early as possible if possible, and rather leave a day earlier if there is any doubt about the weather. If I was to do this trip again (I’m sure I will), I will land at Cape Town international (FACT), suck up the higher landing fees and then be able to (a) access the aircraft whenever needed and (b) be able to depart before sunrise (Morningstar has no airfield lighting).

Direct route home

For a first long cross country trip I think it went really well. It had moments of frustration and times when I was quite anxious about the effects of the turbulence on continued flight. But that feeling when your destination comes into view after a long trip and you know you’ve made it? It’s fantastic. 

Flying to a Congress in Cape Town

Having an aircraft means somewhat more flexibility in terms of using general aviation to get to where you want on (more or less) your own terms.  Of course, having an aircraft also means you can make totally financially unjustifiable trips on (more or less) your own terms. 

I tried to do a long cross country to a congress I was presenting at in August, in George. George is an airport with a bit of a reputation – on a small plateau on the coast behind some rather imposing mountains and some rather fiddly airspace which I’m told ATC does not ever allow you to penetrate on a VFR flight plan. I was going to be doing this trip in a rented SR20 but as it turns out the weather forecast was very marginal and I didn’t fancy my chances of getting in. Also, it’s not really fair to congress organisers to have a speaker who may not make it due to weather – so I binned that trip and flew commercial. 

When this congress in Cape Town came up it looked like a much more viable option for flying myself. Firstly – no really large mountains, secondly summer weather which at that part of the coast is not characterised by cloud or thunderstorms, and thirdly access to my own aircraft (so no demurrage costs for the days it would be sitting on the ground). 

Johannesburg to Cape Town is well within the limits of the Sling4 – range is around 750nm and with a flight plan distance of 665nm this would be easily doable. The prevailing winds tend to flow west to east so this would reduce the range somewhat and my personal limits call for never landing with less than an hour’s fuel in the tanks so a refuelling stop would be required along the way. I settled on FATP – New Tempe in Bloemfontein – about 95min flying time from Johannesburg.

Date of FlightAircraftRouteDistance (nm)Time(hrs)Total(hrs)
9 November 2018ZU-IBM (SLG4)FATA(Tedderfield)- FATP(New Tempe)2022,1101,9

The plan was to leave just after sunup on the Friday morning. The plan was thwarted by various delays including me leaving my snacks behind and having to source some more food for the trip. By the time I departed Tedderfield the sun was well up – I need to plane better and arrive earlier – prefilghting and the other admin related stuff I had to do delayed me too much. 

PreFlight done – ready to go.

The flight to New Tempe is 200 odd nautical miles – easy airspace – and with not a hill in sight – the air was clear and smooth and I thought this was going to be an easy trip. And it was – at least as far as FATP.

The Vaal River near Parys

Upon arrival at FATP New Tempe I fuelled up (sadly only Avgas available) – 41litres used for the 200nm trip – around 10Gallons.  Some R66 turbine helicopters were also fuelling up – one of the pilots was wearing the whitest Flight suit I have ever seen. The equivalent of a white tuxedo.

Two turbine Robbies (R66)
$4.00 – The processed meat special!
Time to get going again!
Date of FlightAircraftRouteDistance (nm)Time(hrs)Total(hrs)
9 November 2018ZU-IBM (SLG4)FATP(New Tempe) to Morningstar4954,5105,4

By the time breakfast had been consumed it had got very hot, so I was pretty stoked to be on my way again. Bloemfontein cleared me straight through their airspace which was a plus – but then the turbulence started in earnest and even climbing to FL105 didn’t help much. This part of the world is renowned for its gliding conditions and its easy to see why – had updrafts in excess of 600fpm at times! My smooth sailing plan was but a memory and I was basically holding on for dear life at times. Having a loaded weight of about 600kg doesn’t help when its bumpy.  For the first time I was glad I was alone – I can’t see passengers enjoying this too much! 

Still, the discomfort was more than made up for by the views and the starkness of the scenery. We settled down at about 125-130kTAS which worked out to about 110-115 kts GS – not too shabby. It’s no Mooney but it does the job.

VanderKloof Dam
Sutherland Observatory

Then it was time to get down. Under the category of “if you don’t ask…” I requested a VFR transition through the Cape Town TMA – the reason for this is that their TMA is 2000ft AGL and the mountains in the area while not high are certainly intimidating to some extent and permission to transit the TMA would keep me higher for longer and allow a more gradual descent while being well clear of the mountains. Fortunately they were happy to allow this and my arrival into Morningstar airport was very straightforward. 

Winelands near Tulbagh

Upon arrival at Morningstar I tied IBM down and then tried to put the canvas canopy cover on. I wish I had a camera for this. The wind was howling from the starboard side of the plane and every time I had the canopy in place and I walked round to tie it on it would blow off. Eventually I stuffed it INTO the cockpit and covered everything with it. For reasons best known to the manufacturer it has Velcro straps which are entirely inadequate for the SouthEaster.

Tucked into visiting parking at Morningstar – Note lack of cover!
OzRunway trip map

This was the furthest I’ve ever flown myself, my longest single leg, my longest trip and the first time at two new airports. A good day’s flying! 4h at FL105 with a DA of 12500ft took it out of me somewhat – I do carry a pulse oximeter in the aircraft and used it regularly – never below 91% but still I was exhausted. 

A new rating

So I have a new type on my license – and some endorsements to go with it! I recently spent two days at Wonderboom Airport (FAWB) getting rated on the Sling 2.

The Sling is a locally (South African) designed and built aircraft. It’s nominally a light sport aircraft but as configured it requires a PPL to fly as the maximum takeoff weight is over 600kg. Interestingly the same aircraft, with one wing tank removed will have a MTOW < 600kg and can be flown on a recreational pilot license as a light sport airplane. 

It’s also quite different from the Cirrus I have done all my training on to date. Of course, it’s much lighter, all metal and has a significantly different engine? How different? Well, it’s a Rotax 914 – a 1.2l 4 cylinder producing 115hp compared to the Continental 0-360 6 banger on the Cirrus. It’s also turbocharged and the prop is a variable pitch constant speed unit (Yes, the Cirrus had a variable speed CSU but with no direct pilot control). Importantly, it burns MUCH less fuel – 20litres per hour compared to the 50-65litres per hour on the Cirrus. And it will burn MoGas happily too. 

To obtain the conversion onto the Sling was not an easy matter. Firstly, there are a lot of flight schools operating Sling 2s. There are only 2 in the country that have the Sling 2 914 Turbo on their ATO. Thus I had to travel to Wonderboom, which is a great airport. Unfortunately it is 90km from my house. Not so good. I did the conversion through FliteCare who were fantastic – they could accommodate me at short notice, and their desk staff were amazing. 

I first needed to have briefings on the Sling aircraft itself – concentrating on the many differences between it and the Cirrus – this took about an hour, then it was time to dive into the nitty gritty of turbochargers and variable pitch propellers.  Turbochargers are easy to understand – once you figure out how the wastegate works and the differences between the hot and cold sections. The variable pitch propeller on the other hand I found to be a lot more complicated. It’s bloody brilliant engineering but seems very complex. My biggest problem is remembering the difference between fine and coarse pitch which I find counterintuitive. 

As it turns out, the intricacies of the variable pitch prop are moot in the Sling because it has a very clever system to adjust prop pitch. Firstly, instead of being controlled by oil pressure and springs, the pitch is adjusted electrically by servos in the hub. And there is no pitch lever as would be suspected, but a pitch control instrument on the panel which has a knob to select T/O, Climb, cruise, hold, and Feather. One can also bypass the selector and adjust pitch manually should the control unit fail – this is done with a rocker switch. Once a setting is selected, the CSU adjusts pitch to maintain the required RPM on the prop. Because the Rotax is a geared engine, engine RPM does not directly reflect prop RPM – so prop rpm is not set, but the CSU will indirectly control engine RPM. 

Speaking about engine RPM – this is high! A regular aviation mill will turn at about 2500-2700RPM. The Rotax idles at 2000 and will go all day at 5500. An interesting feature about the 914 is that full power is actually 100hp with an additional 15hp available when you push the throttle through the gate – allows 115hp for up to 5min – would primarily be used for takeoff and initial climb to 300ft AGL and obviously for the go-around. In the gate position the engine is turning at 5800rpm. 

After the briefings, it was time to fly. The conversion requires upper air work, simulated engine failure and at least 5 landings. Preflight is fairly standard with the addition of a prop control unit check – cycle from full fine to coarse with the engine off (remember those electric servos?). The other very different aspect is the dry sump oil system – oil is stored in the oil tank – so in order to check the oil one needs to ensure all the oil is in the tank and not in the crankcase.  This involves turning the prop by hand (check mags off, key out master off first!) until the telltale gurgle from the tank indicates that the oil has returned. 

Dragging the plane out of the hangar is a one man affair – really a pleasure. Startup is a non event – fuel pumps on, fuel on and crank. It literally starts like a car engine. Run at 2000 until oil pressure settles then warmup is at 2500 until oil temp reaches 50C. Operating temps are much lower than conventional engine due to the hybrid air/water cooling system. 

Taxiing is much simpler than the Cirrus due to the direct nosewheel steering – so much nicer than the free castoring nosewheel. She’ll roll 2 up at 2500 so the engine can warm nicely en route to the run up bay. Most pre takeoff checks are done on the taxi as they have a reputation of getting quite hot while idling stationary. In the bay it’s final checks, run up at 4000RPM checking the mags (<300drop and <115between), takeoff briefing and then it’s time to fly. 

The best word to describe takeoff is “sporty”. Stabilise at 5500RPM and 100hp then through the gate to 115/5800. Lots of right rudder is required and before you know it, we’re at 48kts and the rotate call. Liftoff at 55kts and best rate at 75 has her climbing away comfortably at about 1200fpm. After takeoff checklist includes setting prop to climb, coming back out through the gate and cleaning up the flaps. 

For the conversion we set off to the general flying area – steep turns are a non event – very easy to keep the nose up. Stalls are reasonably benign but I did detect a slight tendency to drop the wing and not a huge amount of buffet. The (brilliant) MGL Avionics iEFIS unit has an AOA indicator too which is helpful.

Then we did some circuits at Freeway airfield – which has a massive runway which is gravel. Also a non event for the Sling. I may think twice about taking an aircraft I owned onto a gravel strip but certainly it wasn’t an issue on this plane. 

Back to Wonderboom with me having no idea at all of where I was – fortunately the instructor was at home in the airspace. The plan was to do a couple of circuits, but this was foiled by a medium sized Cb cell which decided to discharge itself over the airfield. Conditions on landing were challenging to say the least – significant wind shear and gusts from about 15degrees off the front of up to 25kts. The Sling handled this with admirable aplomb. 

Sadly this meant I had to make the pilgrimage to FAWB again to finish the rating. We banged off 4 circuits easily in the mid morning this week – 2 normal landings (Flap 20), 1 flaps up landing (would really rather not do those….) and 1 short field stop and go. The procedure for landing the Sling is similar i believe to the C172 – cut power just short of the threshold and glide it in. You can’t do that in a Cirrus..  The short field landing we did just to demonstrate it – in the POH it says “short field landings as per normal landing” since the landing distance is about 270m. However, we did a short field approach – flaps 30 and standard piloting, stopped on the runway, and then did max performance short field takeoff – full throttle, brakes off, through the gate and full back pressure on the stick from the moment rolling starts. The nose wheel lifted of at 20kts and we broke contact at 48kts. Lower nose to Vx (75) and then up and away. Very impressive, especially when you look at the airport diagram and see how short the distance was – we landed on 29.

We were airborne before the circled intersection from RWY29

It’s really nice to have excess power available. So I’m now rated on the Sling2 and have endorsements for turbocharged engines and variable pitch propellers. Onward and upward!

I like the night life….

Some of the best video I’ve seen on YouTube of flying is in the evening – after the sun has set. Being able to fly at night obviously extends the useful flying day and also improves the options for waiting out weather and other potential delays. I’m a firm believer in having options to decrease the risk of acute get-there-itis.

 

With this in mind I’m setting off on my first post-PPL rating – the night rating. Interestingly we have the night rating as a separate rating instead of built into the PPL like it is in the United States. The requirements are not onerous but definitely stipulate dedicated experience in the dark – at least 3 circuits at night (I’ll be doing many more), 10 hours of instrument training (5 of which can be in the sim), a 150nm cross country by night and a theoretical exam.

 

As it stands currently, I’ve done 7 odd hours in the sim – all hard IFR flying and have enjoyed it quite a lot – I’m sure it’s the wasted youth playing Microsoft Flight simulator but at least I have some theoretical knowledge to hang onto that experience. So it’s actual night time flying I need – and this is what I did last night…

Date of FlightAircraftRouteIF ActualTime(hrs)Total(hrs)
19 July 2018ZS-ZIP (SR20)FALA(Lanseria, Johannesburg) - FALA1.31.683.6

So. Flying at night. It’s… well…. dark. In fact this surprised me because I was anticipating that the lights on the plane would be better than they are. They’re not great for taxiing on the apron so that took a little getting used to. The lighting on the taxiways at Lanseria is great so that wasn’t an issue. No delays fro other aircraft on the field while taxiing which is always a plus. Run up and pre departure checks were as per normal, although I chuckled at my instructor when she said that we’d aim for the darkest patch off the end of the runway if we lost and engine, we’d turn on the landing light, and if we didn’t like what we saw we’d turn it off again. This did bring home the stark reality of night flying – it’s really difficult to find a safe landing spot should the big fan in front decide to stop. Lining up on 07 you get the sense of how dark it is – a row of lights leading out into almost infinity and just blackness beyond – not a sliver of moon in sight even.

 

 

Performance in ZS-ZIP was pleasantly surprising – 9 celsius outside temp will do that  and climb out was brisk (for an SR20). The instructor had me on the gauges almost immediately after takeoff and I flew the numbers – 5deg nose up with 50% flaps at full power gave me just over 85kts (Vy) so we were at CAPS height crossing the 25 threshold which was reassuring. Then it was head down in the cockpit. The aim of the flight was instrument navigation introduction – I’ve done lots of sim time but this felt somewhat easier I thought. We did a number of VOR radial intercepts under the Lanseria TMA – I must say that the VOR intercepts are reasonably easy with it being a command instrument – fly to the needle and the only tricky bit is remembering which reciprocal to use (FROM top TO bottom). Then we climbed out into the practice area for some upper air work – clean and configured stalls (no problem) and some steep turns – again not an issue which is quite funny considering how much difficulty I had with them prior to my PPL practical test.

 

Then some timed turns which are challenging – essentially we work out an angle of bank for the rate one turn (TAS divided by 10 plus 6-7kts) which at 130kts TAS works out to be around 20deg. Then set up on a radial, bank in to the rate one bank angle, start the timer and then try and maintain 45deg of heading change every 15seconds – 3 deg per second. Not quite as easy as it sounds but very rewarding to get right. These will be useful later in IF training when it comes to holding patterns and procedure turns. Then it was time for some ADF work. ADF navigation puzzles me from a number of aspects. Firstly, it’s a big drain on my brain to figure out which way to turn each time and secondly, they’re essentially obsolete. They’re so obsolete, in fact that our 2004 model SR20 G2 has no ADF radio on board. As a result, we have to bodge an ADF navigation exercise by using the bearing needle on the HSI to point to a GPS location and then fly using that as an ADF station. It gets the job done and perhaps it’s ADF as ADF should have been.

 

Still, ADF intercepts are fiddly. Intellectually I know it’s a simple case of remembering where one is in relation to the station and turning appropriately. The little tricks – turning away from the desired QDM inbound and towards and beyond QDR for the outbound – do help, but they’re not intuitive – I’m guessing that practice practice practice will be the key to successful ADF navigation. Finishing up with some unusual attitude recovery (again, fun…) I considered we’d done some good work. So what is it like flying at night? I found it really serene – its you and the plane – I didn’t hear any nighttime rough running and the air was smooth (and freezing – note to self – take a better jersey next time) and calm. The lights stretch for miles and the dark patches do feel like they’re reaching up to grab you – I assumed all the dark patches are mountains because why would anyone put lights on a mountain? The best part for me is that the feeling is getting better – i.e I’m flying more by the seat of my pants than I have been before and it feels smoother – I do need to be a little bit less aggressive on my turns – I do tend to roll quite positively which works during the day but perhaps not as well under instrument conditions!

 


 

We decided we were chilled enough and headed back for Lanseria. One scheduled 737 on long final and then we were to roll in onto approach. The night time approach is easier, and harder than I thought. Flying the profile is easier than during the day as less gusts and updrafts but the roundout and landing was very different. The instructor was following me on the controls – we went over the threshold at what I felt was the right height having had 2 red and 2 white on the PAPI the whole way down. Then she says “do you feel like you’re sitting on the runway?” and I say, “Um… yes?” and she says, “OK, go to idle” and we touch down light as a feather – best landing ever I think. Which would be awesome, except in my mind we were about 5feet higher and I wasn’t expecting the touchdown at that point. This confused me a little as I was convinced that one would feel lower coming in at night. There is no centreline marking on the runway so the only visual reference is the side lighting – guess I need to pay more attention to that in the coming flights – which should be two sessions of night circuits. Can’t wait.

 

Safe flying!