Rotax 912 series oil filter – new service bulletin

Rotax has issued a new mandatory service bulletin covering their oil filters – SB-912-071.

Due to a manufacturing deviation, the sealer gasket on the oil filter may leak, causing possible loss of oil pressure and oil.

If your 912ULS engine number is within the series from S/N 9 569 542 up to S/N 9 569 782 inclusive, or you have service replaced your oil filter since June 2017, you need to check the filter. If it has a green mark in the specified location, the filter is OK. If not, check for leakage and if any is seen, the filter must be replaced immediately. Even if there is no visible leak, the filter must also be replaced immediately on listed engines.

If there is no green mark on the filter, no leakage and the engine is not listed, the filter should be replaced within 25 engine running hours or within 200 days from 01 November 2017, whichever occurs sooner.

Here is a link to the service bulletin which gives full details: SB-912-071
Here is a link to the listed 912UL & 912ULS engines affected: SB-912-071UL

Urgent Rotax safety bulletin

Rotax has issued an urgent and mandatory service bulletin on their 912/914 series engines. It applies to a limited selection of engines built between June 2016 and October 2017 – check your Foxbat/Vixxen 912ULS engine number against the list below to see if you are affected.

(A) from S/N 6 785 971 up to S/N 6 786 198 inclusive
(B) from S/N 6 786 501 up to S/N 6 787 000 inclusive
(C) from S/N 9 569 001 up to S/N 9 569 690 inclusive
(D) from S/N 9 569 693 up to S/N 9 569 702 inclusive
PLUS S/N 9 569 823

In summary
Rotax reports that deviations in the manufacturing process of the valve push-rod assembly may cause partial wear on the rocker arm ball socket. This wear could lead to a rocker arm cracking/fracture which in consequence may lead to a malfunction of the valve train. Possible effects are rough engine running or an unusual engine operating behaviour.

The bulletin requires the removal of the rocker covers of affected engines and an inspection – and if needed, replacement – of the valve pushrods.

In simple terms, if the pushrod ends are a silver-ish colour, they are OK. If they are black they will need to be replaced.

Time frame for completion of the bulletin is:
– either at the next scheduled service
– or if a scheduled service is not due, within the next 25 hours of engine running time
– or if 25 hours running time is not completed, by 30 April 2018 at the latest

Here are links to the Bulletins:
What needs to be done:
Which engines are affected:

If you believe your engine is affected, please contact Bert Flood Imports, the Australia Rotax engine agent, for more information.
Bert Flood Imports phone number is: 03 9735 5655

Tie-down rings for A22LS & A32 aircraft

With Aeroprakt factory approval, we have developed a kit of tie-down attachments for A22LS and A32 aircraft. This is available as a retro-fit kit or as an installed option on new aircraft.

The kit consists of all the parts you need to add a tie-down point to the top end of each wing-strut and to the tail of the aircraft. There are full fitting instructions and also a copy of the factory Letter of Approval, which you’ll need, to keep the aircraft legally an S-LSA. Please note – non-approved changes to LSA planes mean they revert to ‘Experimental’ LSA – meaning you cannot use them for flight training and/or hire.

The photo here shows one of the strut rings but click here to take you to the Foxbat photo gallery where there are some bigger, higher resolution photos.

We are also developing a nose wheel tie down plate for use if you have to park your aircraft outside for more than a night or two – watch this space!

Cost of the retro-fit tie-down rings kit is A$295 including GST and postage inside Australia. As a fitted option on new aircraft, the price is A$335 including GST.

NB: this kit is not suitable for A22L aircraft.

Please contact Foxbat Australia at if you wish to order a kit.



Aeroprakt A22/A32 Weight & Balance calculator – update

UPDATE – by popular demand, the Weight & Balance calculators now enable fuel to be entered in litres – the calculator will work out the fuel weight and give you a gross weight and CofG as before. Hope you find that more useful.

We have developed a simple MS Excel spreadsheet to enable A22 and A32 owners to calculate easily their weight and balance before flight. For ease of use, all cells except the fuel volume in litres and weight values for the basic empty aircraft, pilot, passenger and baggage have been locked,

All you need to do is enter the fuel in litres and kilogram weight figures for your aircraft and the sheet will calculate your gross weight and the CofG position for you.
If all is within limits, the gross weight and CofG figures stay green. If they are outside limits, they turn red.

Please email me if you want a copy for your A22/A32Weight & Balance calculator – please specify if you want an A22L Foxbat, A22LS Foxbat, A22LS Kelpie or A32 Vixxen sheet as they are all slightly different.

Ballooning & floating?

Probably the most common comments I get from student pilots – and quite a few experienced pilots too – are about their perceived skills needed to land a light sport/recreational aircraft. In many cases, pilots make comments like: “I pulled back on the controls to flare and the aircraft just ballooned” or “it just seems to float and float along the runway; it just doesn’t want to land”.

Both of these events when landing an aircraft – ballooning and floating – have their own dangers for the pilot, which if not anticipated and handled correctly can result in a bent aeroplane…or worse.

So here are a few tips on how to get it right.

In simple terms, almost all balloons and floats during landing are caused by excess speed over the landing threshold. Unfortunately, many instructors have a habit of telling their students to add 5 or 10 knots to their approach speed ‘for safety’. In reality, in light sport aircraft in ‘normal’ conditions, they are often actually reducing the margin of landing safety by doing so. And this habit of adding speed to the book figure becomes instilled as a very hard-to-break habit. My own pilot training, now many many years ago, involved adding approach speed in certain circumstances and, even now, I have to fight the impulse to add speed when landing in the A22LS Foxbat and A32 Vixxen.

Let’s go ballooning
So, what’s wrong with more speed? There are two main reasons but first, remember light sport and recreational aircraft are very low weight (read: low inertia) aircraft. So, like a small car, these types of aircraft will change direction much more quickly than a limo, a ute or a truck. Not that I’m suggesting your average Cessna/Piper etc are trucks…. As a result, when landing, the controls are much more effective than bigger GA aircraft. At only slightly faster speeds the controls are even more powerful, so if you are too fast when you pull back to flare, the aircraft will not just flare, it will start to climb again, even with the engine at idle. This is called ‘ballooning’. When you go ballooning, the impulse is to push the nose down to reduce the sudden climb. Unless you are very quick (and/or experienced) you’re likely in for a bent nose leg and/or busted propeller. Another alternative, just holding back the controls during the balloon, can result in a stall from an ‘unsuitable’ height above the runway, leading to a (very) heavy landing, which could damage the landing gear or worse.

How about a bit of floating?
Next reason why too much speed is dangerous: even if you flare correctly without ballooning, the aircraft is still going too fast to land. Instructor: “Just try to skim the runway; don’t let the aircraft land; try to keep it flying as long as you can, slowly pulling back on the controls until the aircraft slows and the main wheels touch down”. This is all absolutely fine, unless you are carrying excess speed, in which case you’ll end up flying a long way down the runway before you touch down. And skimming along the tarmac (or grass) at relatively slow speed for a few hundred meters at just a few feet of height is tricky enough for an experienced pilot, let alone a novice. Throw in some cross wind, and/or a gust or two, and the risk of disaster rises exponentially! After a period of ‘skimming’ without landing, there is a huge temptation to let the nose drop a bit (or worse, push it down), just to get the wheels on the runway, and this can have two potential results: (a) because you’re still going too fast, the nose wheel touches down first and you’ll bounce/balloon, or (b) the impact will bend the nose leg and maybe bust the prop – if you’re lucky.

There are remedies for both ballooning and floating after they start but the easiest solution is not to let them happen at all!

Calculating the correct threshold speed
Which is where we get back to speed. There’s a GA rule of thumb about landing speed over the threshold. This says you should aim for about 1.3 times stall speed in landing configuration. As an example, with a stall speed of 45 knots the aim is (technically) 58.5 knots over the threshold – which is usually rounded to 60 knots. With low-inertia light sport aircraft, which have lower landing speeds, it’s probably safer to go for about 1.75 times stall speed, as wind gusts can be a much higher proportion of approach speed. So, for a stall speed of 28 knots (A22LS Foxbat) the threshold speed should be about 49 knots – which is exactly what the pilot manual gives. Note – this is 20 KNOTS above the stall speed!! If you come in at 55-60 knots over the threshold, you are flying about twice as fast as the stall speed – no wonder the aircraft is difficult to land!

What a drag
There are big differences in drag between aircraft. And drag affects how quickly the aircraft slows down when you throttle back for landing. The more the drag, the quicker the aircraft will slow down and vice-versa. To some extent, high-drag aircraft are easier to land than their more slippery siblings. As you cut power and round out to land, they will slow down more quickly, so if you are a few knots over the correct speed, they will help you out by slowing quickly. However, the more slippery the aircraft, the more accurate you need to be with the threshold speed; this is because if you are faster than you should be, the speed will not wash off quickly and ballooning and floating become much more likely.

As a comparison, our A22LS Foxbat is much much draggier than the A32 Vixxen. This is clearly evidenced in the fuel economy and cruise speeds. While the book figures for landing threshold speeds are much the same at 49 knots, coming in at 55 knots in the Foxbat will still allow you a reasonably easy landing. Try it in the Vixxen and because of its low-drag airframe, you’ll probably do a lot more floating. Add yet another 5 knots ‘for safety’ and even the Foxbat will take a while to land and the Vixxen will take you all the way down the runway into the fence at the end.

Landing weight
There’s an important additional piece of information needed here – the landing weight of the aircraft. All manufacturers quote stall speeds at maximum gross weight – for light sport aircraft, this is 600 kgs. If the stall speed is 28 knots at 600 kgs, it will be noticeably slower at (eg) 450 kgs actual weight, which in an A22LS Foxbat equates to the aircraft with one pilot and 50 kgs (70 litres) of fuel. In fact, it could be as much as 3-4 knots slower. Re-calculating the approach speed for this weight: (eg) 25 kts x 1.75 = 44 kts.

Hopefully, instructors  teach their students properly about the difference weight can make to stall – and thus landing – speeds. This is particularly important for light sport aircraft, where the pilot, passengers, fuel and baggage make up a much bigger proportion of the weight and therefore have a much more significant effect on speeds than heavier GA aircraft.

Finally, a point about wind. I’ve often heard it said you should add 5-10 knots to your approach speed if the wind is across the runway and/or gusty. The idea being that if the wind suddenly drops during your approach, the aircraft is still going fast enough to keep flying above stall speed. In heavier GA aircraft, this may well be valid, as using the throttle to regain speed to arrest the momentum of a sudden descent takes time. However, modern light sport aircraft are much more responsive to throttle than their older GA counterparts, so I would never add more than 5 knots to the ‘book’ approach speed in a cross or gusty wind and use the throttle to stop descent quickly if a sudden drop occurs due to a gust.

In summary – read the pilot manual for your aircraft to check the threshold speed for that specific type – do not rely on rules of thumb, like “all aircraft are OK at 60 knots” down final and over the threshold. If the manual gives 49 knots at gross weight stick to it and – if it’s a light sport aircraft – even a bit slower if you do not have a passenger and/or lots of fuel. If you don’t stick to the book speeds, you are looking for trouble and for sure, you’ll end up ballooning or floating and sooner or later you’ll bend something. Hopefully, not yourself or your passenger!

KievProp propeller balancing

Here’s a great little video about how to statically balance your KievProp – ie off the aeroplane. I suppose the technique could be used for any type of propeller. It certainly works here!

As a matter of interest, you can also dynamically balance your propeller – ie when attached to the aeroplane, with the engine running. However, this does need a piece of electronic kit (which is not cheap and simple) which in principle works in much the same way as the static balancer.

Overall, for an inexpensive and excellent balancer, the static approach works well.

PS – be sure the carburettors are correctly balanced (ideally with the engine running) and the blade pitches are all exactly the same…not even a skerrick out!

As usual, click on the picture or the link to get you to the video.

How to destroy your aeroplane…

…and have a lot of fun, in a few easy steps.

The first golden rule to remember is that when it comes to your aeroplane, you know best! Most manufacturers generally do not design aircraft the right way and if you ask around, you’ll almost certainly find an engineer who will agree with you. So – don’t waste time reading the pilot or maintenance manuals, they are only there because the manufacturer legally has to issue them and they are full of antiquated procedures anyway. These manuals don’t carry anything like as much weight as your own knowledge and experience, seasoned with a liberal dose of advice from mates, who also usually know much better than manufacturers, engineers and the like.

Here are a few more specific tips on how to destroy your aeroplane:

When you park, don’t bother to secure the controls or control surfaces. If possible ensure you park the aircraft facing downwind so that even a light wind will help you get those ailerons, elevators and rudder flapping nicely – but the stronger the wind the better! Once the control surfaces have hammered up and down a bit – allow at least a couple of hours if possible, overnight is better – the hinges, control rods (or cables) and connections will be well stressed. If you’re lucky you might even pre-fracture a connection somewhere in the system which, hopefully, you won’t find out about until you’re in the air – it’s great fun flying an aeroplane on the rudder or aileron trim, assuming they aren’t busted too! Remember, if the aircraft manufacturer has supplied a control lock, lose it as soon as you can! And it is so fiddly to tie the controls with the seat belts, it’s best not to even think about using them!

Leave the doors or cockpit canopy open at all times when you aren’t flying. This helps to air out the aircraft, particularly on a breezy day. In fact, the stronger the breeze the better, as it will likely slam the doors or canopy closed for you. If all goes to plan, it may even damage the hinges or latching mechanism – it’s a wonderful experience to have a door or canopy come open when you’re flying! All the maps fly out and sometimes the aeroplane can get a bit tricky to handle, specially when you try to land. If you are extra lucky, the door slam may even weaken or damage the door frame, helping it to unlatch in flight even if you think you closed it properly!

Always clean the screen and windows with household products – Mr Sheen, Windex, truck wash, polishing creams, they are all good at attacking aviation polycarbonate or acrylic. Even better, wait until there is a good layer of dead bugs and dust on the windscreen and then use a slightly moistened cloth – a kitchen ‘wash-up’ sponge is better – to rub off the mess. If you are diligent, you can create some wonderful swirly patterns which look great when you fly towards the sun. After a time, you’ll get used to heading away from the sun most of the time, so an unexpected landing towards the west at the end of the day will be all the more exciting, as you guess where the runway threshold is.

If at all possible, keep your aeroplane in a damp environment – ideally put a few old bits of carpet over an earthen hangar floor and ensure they stay reasonably wet. That way, most aluminium and steel parts can start to corrode as quickly as possible. Even if you own a glass fibre aircraft, a damp hangar is still a good idea; even plastic planes have metal control systems and engines. And as every boat builder will tell you, moisture attacks glass fibre too! Here’s an extra tip for glass fibre plane owners: park your plane out in the direct sun as much as possible, particularly when the temperature rises above 25 celsius. That way, the composite material has the best chance of  UV decay. A good wheeze is to paint a dark colour on white composite wings and fuselage – the temperature differential in hot sun really accelerates the breakdown of the fibres.

If you have an auxiliary fuel pump – leave it switched on at all times! Even if the pump supplier says otherwise – after all, what do they know? Remember, the pilot always knows what’s best for their aeroplane, and the aux fuel pump is a good way of ensuring continuous fuel flow to the engine. A good time to switch on most pumps is at the top of a long descent; the slow rate of fuel flow cooling the pump might enable it to heat up and, if you’re lucky, could even start melting the insulation round it. This is terrific fun, as the cabin fills up with smoke, which might be smelly but at least it generally isn’t toxic. If you really want to let rip, leave the pump on after it starts smoking and it might even catch fire, so you’ll have a real emergency to tell your mates back home about.

Wherever possible take the opportunity to modify the aircraft from the condition the manufacturer specified. Here are a few tips:
– if the prop is pitch adjustable, coarsen the pitch to the maximum. You won’t get more cruise speed, the take-off and climb will suffer but hey! it will really stress out the gearbox and crankshaft
– if you can, redirect any drain and vent tubes to places that wizened old mechanics tell you. For example, carburettor vent tubes can be lengthened so they pass outside the cowling into the airstream. It plays havoc with the carburettor float levels but at least any vented fuel goes straight out into the slip stream instead of inside the cowling
– here’s a good one: replace the aviation (pink) brake hydraulic fluid with motor brake fluid (pale yellow). It’s much easier to get, it’s cheaper and the brakes will only seize up after a few weeks
– for you electrical buffs, try replacing fuses with the next size up; it helps to minimise the chance of an inconvenient fuse blowing when you don’t have a spare
– if the throttle lever seems a bit short, get an old piece of aluminium and bolt it on to make it a more comfortable length; don’t worry if it now fouls another control, it likely only does so at extremes and how often do you need those?
– wherever possible, replace fixed nuts and bolts with quick-release fasteners; they are weaker and there’s a reasonable chance they will ‘quick release’ when you least expect it, giving you some extra in-flight fun – well worth the effort to install
– a lot of people like to fit bigger tyres because they think (a) their plane looks sexier with huge tyres and (b) they think it makes it easier to land on bumpy surfaces. Because of the extra leverage from the radius of the bigger wheels, you’ll find the aircraft pulls up more slowly and/or wears out the brake pads three times as fast – either way, go for the fat tyres!

Last but by no means least, try to avoid pre- and post-flight inspections. First, they take up such a lot of time when you could be flying and, second, you never find anything anyway. If you have to check anything at all, maybe limit it to a look at the oil level – but only if there’s a little hatch to reach through; it’s such a hassle taking off the cowling to look at the engine because it never goes wrong. Does it? I mean, it’s not as if your life could depend on it….