Cleaning A22 Foxbat and A32 Vixxen windscreens

Over the last couple of years, we have received reports of broken windscreens on a very small number of Aeroprakt aircraft in Australia. A couple of these were definitely due to bird strikes. However, the cause of a couple of others has never been finally agreed.

The factory reports a very limited number of screen failures in the rest of the world – I believe two or three more – in addition to those reported in Australia. This is out of a total world fleet of over 1,100 aircraft spanning 22 years of production.

In an effort to establish potential causes, and thus introduce preventative measures, we have agreed to publish as much information as possible and seek owner responses where appropriate.

First of all, the factory wants to emphasise the following points:
1. The windscreen design and material have proven themselves on hundreds of Aeroprakt airplanes. Screen collapse cases are extremely rare and have never been associated with the design, but usually pre-existing cracks.
2. Current windscreens are made not of polycarbonate plastic but of PET (Polyethylene terephthalate), so any ‘polycarbonate approved’ cleaner may not be suitable for PET.
3. The effect of unsuitable cleaners (including gasoline, Windex®, Mr Sheen®, solvents which may be suitable for acrylic screens or any other non-PET approved solvents) on the structural properties is such that the PET glass may become brittle (crack-prone) in stressed areas (although in non-stressed areas it has no such effect).
4. The factory does not make oversize rivet holes in the glass because it makes no sense as the rivets compress – that is, produce stress in – the glass anyway.
5. All-aluminium rivets are used to secure the windscreens. This means every part of the rivet is aluminium – including the shaft, which is not steel, as per regular ‘pop’ rivets.
6. The recommended sealant for PET and polycarbonate windscreen replacement is now an acrylic transparent sealer such as FulaSeal 701, not a silicone sealer, which should be used sparingly. Excessive use of sealer can potentially weaken the screen.
7. Finally, a thicker glass is not a good solution as it will be under even higher stress in the areas where it is formed to the required shape. Therefore it will be even more prone to cracking.

In the past, based on local engineers advice, it has been Foxbat Australia’s understanding that the windscreens of A22 and A32 aircraft were polycarbonate sheet and as part of our new owner pack, we have included a canister of proprietary polycarbonate screen cleaner. We have also in good faith recommended these cleaners to existing owners. None of these products expressly forbids their use on PET, nor can we find any information regarding their suitability for PET – indeed, they all make generic statements like ‘suitable for cleaning all plastics’.

However, at the present time, we strongly recommend that owners/pilots of Aeroprakt aircraft stop using these types of cleaner on their windscreens until such time as their manufacturers confirm without reservation and in writing that they are suitable for PET.

So how should you clean your Foxbat/Kelpie or Vixxen windscreen?
1. We recommend cleaning PET (or polycarbonate) plastics first with a mild solution of soap or detergent and warm water. It is also possible safely to use a specialty cleaning product such as Novus® No.1 or Brillianize.
2. DO NOT use window cleaning fluids with ammonia (such as Windex®, or Formula 409®), Mr Sheen®, gasoline, denatured alcohol, carbon tetrachloride, or acetone, which will cause the plastics to craze with minute cracks.
3. DO NOT use so-called ‘aviation approved’ screen cleaners as these may have been formulated for cleaning other types of plastics.
4. Begin by gently blowing away any loose dust, dirt and dead bugs from the surface. DO NOT use a pressure washer on any part of the aircraft, including the screen.
5. DO NOT use proprietary chemicals (such as ‘Bug Off’) to soften and remove dead bugs from the screen. Simply spray a weak solution of soap and water on the screen and let it soak for 5-10 minutes, re-spraying if needed to keep the surface wet. Then wipe with a wet non-abrasive/non-contaminating/lint-free soft cloth, microfibre cloth, or cellulose sponge. Rinse well with plenty of clean, clear water. You may need to repeat this process a couple of times to remove all dried-on dead bugs.
6. To give a final clean to the screen, apply the specialty cleaning product (or a weak soap and water solution) with a dampened non-abrasive/non-contaminating/lint-free soft cloth, microfibre cloth, or cellulose sponge.
7. Rinse well with plenty of clean, clear water.
8. Pat dry with a chamois leather, damp cellulose sponge, or microfibre cloth to prevent water spotting.
9. Repeat this process regularly to ensure there is no build up of dirt on the windscreen. If possible, clean a dirty screen immediately after flight to stop dirt etc hardening during the time before you next fly.

Thank you for your attention – please leave a comment below if you feel it’s appropriate.

 

Light Sport Aircraft Maintenance

It is my belief that today’s recreational and light sport aircraft need more careful and meticulous maintenance than traditional ‘rag & tube’ ultralights and typical single engined GA aircraft.

Over the last 15-20 years or so, recreational and light sport aircraft have become much more GA-like in their looks and construction, compared with traditional utralights of old.

Their weight and complexity has increased almost beyond the imagination of early ultralight owners; their airframes have become more and more GA-like, with concealed control systems, engine bay ducting which hides many key engine components, digital instrumentation, auto-pilots and the like. Yet recreational aircraft owners and pilots are still permitted to ‘do all their own maintenance’*.

Crucially, recreational and light sport aircraft have to be designed and built to fit under a specific gross weight limit. There is also a maximum empty weight formula related to the maximum gross, which effectively limits the empty weight of a 2-seat aircraft to around half that of a typical 2-seat GA aircraft. As a result, manufacturers have to do everything they can to minimise empty weight – usually by using light weight materials and making components as strong as they need to be, but no stronger.

This lightweight approach is not in itself an issue – indeed it has enabled the design and manufacture of some wonderful aircraft. But in reality, ‘cheaper and lighter’ means you have to be much more thorough with your inspections and maintenance.

Why?

Because the metal is thinner all round; because so-called ‘carbon fibre’ aircraft actually contain very little carbon fibre (if they really were mainly carbon fibre, their cost would be astronomical); because cables are thinner, because engines are smaller/lighter/more highly stressed, because propellers are typically composite not metal; landing gear is lighter; bearings are smaller, tolerances are tighter; and because some of their systems are quite different from typical GA aircraft, and on and on…

Although RAAus is working wonders to improve the safety of aircraft registered with them – particularly focussing on maintenance issues and authorisations to maintain*, I still have considerable doubts as to the maintenance capabilities of many RAAus Aircraft owners, who likely have little or no aircraft maintenance knowledge and experience. I myself know the A22 and A32 airframes inside out but I do not feel at all confident I could safely maintain one.

For example do these owners know:
– how properly to lockwire a bolt, and what thickness and type of wire is required?
– how to measure and adjust the tension of a control or structural cable?
– how and when to use a torque wrench correctly?
– the standard torque settings for each size of bolt?
– how and when to check static and dynamic carburettor balance?
– how to check the friction on the Rotax gearbox clutch?
– how to make sure the ends of a cable are still securely swaged?
– how to measure correctly the strength of the fabric covering on a wing?
– how to open and examine properly an oil filter after an oil change, and what to look for?
– how to check a control or structural cable for internal abrasion and wear?
– how and where to look for cracks in metal/composite/wooden airframes?
– where to place a jack to raise their aircraft?
– how to decide when to replace an ‘on condition’ item?
– what constitutes ‘acceptable’ and ‘unacceptable’ wear in an item?

Not to mention possession of all the tools needed to do these jobs properly?

Now, I’m aware of many aircraft in our Aeroprakt fleet with well over 3000 hours on them – with no particular problems. As I say, maintained properly, recreational and light sport aircraft can continue flying safely for many thousands of hours.

But if you are going to maintain your own aircraft, get proper training to do so – if you skimp on maintenance or try to save money by doing it yourself when you don’t really have the capability, at the very least your aeroplane won’t last as long as it should. And at worst, it will be your life (or that of the pilot) that’s threatened.

* Owners of RAAus registered aircraft may maintain their own aircraft provided they have an L1 Maintenance Authority (sometimes called an ‘Owner-Maintainer’ authorisation). Details of this are available on the RA Australia website at http://www.raa.asn.au  under the member section ‘Member Training’

A22L Foxbat gross weight increase

I have good news for all Australian owners of A22L (450 kilo MTOW limit) Foxbats!

With the new RAAus MARAP system (Modification and Repair Approval Process), a review to increase the gross weight limit (sometimes called the maximum take-off weight (MTOW)) of RAAUS  registered Aeroprakt A22L Foxbat aircraft from 450 kilograms (472.5 kilograms if a ballistic rescue system is fitted) to 525 kilograms has been conducted and now approved.

During the review of the A22L for an increase up to the 525 kilograms  MTOW there is a small ‘G’ limit penalty: the maximum limits are reduced from +4G and -2G to +3.6G and -1.8G respectively. In effect, this means you need to observe manoeuvring and rough air limits closely to ensure you do not exceed these lower limits.

No structural or other changes are required to the aircraft.

To obtain the increased weight limit on your A22L aircraft, please contact the technical team at RAAus – phone number 02 6280 4700 or email to tech@raa.asn.au – and request the necessary documentation. This includes a supplementary page for your pilot manual and an entry to the manual revisions page.

RAAus will make a charge for this service but I’m sure you’ll find the extra – legal – 75 kilograms well worth it!

Please note, this increase is not relevant to the Aeroprakt A22LS Foxbat, which already has a gross weight limit of 600 kilos and ‘G’ limits of +4 -2

Aeroprakt issues rudder cables safety alert

Example of cable damage


Following two rudder cable breakages on A22LS aircraft, the Aeroprakt factory has issued a safety alert covering all A22 and A22L aircraft with over 500 hours engine running time and all A22LS and A22L2 aircraft over 5 years old or over 500 hours engine running time.

The alert requires an urgent check of both left and right rudder cables to ensure there is no wear or fraying of the cables, particularly close to the pulley guides. If any wear is seen or broken strands are found, the rudder cables must be replaced.

Click here to download a copy of the alert for A22 and A22L aircraft.
Click here to download a copy of the alert for A22LS and A22L2 aircraft.

Australian owners should contact Foxbat Australia for more information or replacement cables. Owners in other countries should contact their local dealer for support.

A32 Vixxen door latches – safety bulletin

Aeroprakt has issued a safety bulletin covering the door latches on A32 Vixxen aircraft, serial numbers 02-28. Compliance with this bulletin is required before the next flight of the aircraft.

Click here or on the drawing above for a copy of the bulletin: SA-A32-03 Door Latches

Aeroprakt A32 demo flight

Via the cockpit video recorder, follow Yuriy Yakovlyev, A32 designer, Aeroprakt CEO and gold award-winning pilot as he takes the A32 through a demonstration flight routine at the 2017 Krakow Airshow in Poland..

It’s interesting to watch Yuriy’s use of throttle and flap and his control of airspeed throughout the 5-minute routine. This video shows what the A32 can do when flown by an experienced pilot.

However… PLEASE NOTE: most of the manoeuvres in this flight sequence are illegal in this type of aircraft in Australia! DO NOT try this at home – remember, Yuriy has many thousands of hours flying experience, not only in his own Aeroprakt factory aircraft but in many other types too.

As usual, click the picture or on this link to see the video: Yuriy flies the A32 at Krakow, Poland

Tyabb Airshow

Well, how quickly have another 2 years sped by? It’s time again for the bi-annual Tyabb Airshow, to be held this year on Sunday 11 March 2018. Gates open at 08.30 and the air display starts at 11.30. The theme of this year’s show is ‘War & Peace’ and there will be many of the old warbirds, for which Tyabb is famous, on display on the ground and in the air. In addition, many Tyabb hangar owners will be opening up their doors to show aircraft old and new.

The airshow this year is sponsored by BP and Eastlink, as well as the Peninsula Aero Club, which has a proud tradition of supporting local community service clubs from the proceeds of their airshows.

The 2018 Airshow is no different with the major beneficiary to be Riding for the Disabled (RDA). RDA Victoria is a not-for-profit organisation that enables individuals with a variety of disabilities, ages and backgrounds to develop independence, a sense of freedom and to reach their equestrian goals, through adaptive coaching techniques and equipment.

The Aero Club will also be supporting the Tyabb CFA, a vital service for all of us, the Mt Eliza Lions Club which exists to support the comminity through a variety of initiatives and the Tyabb Football & Cricket Clubs which serve local youth.

You can save $5 per head by purchasing your tickets on line by clicking here. This will also save you having to queue at the gate to get into what is always a very popular show.

Foxbat Australia will have several aircraft on static display, including the Kelpie and Vixxen, as well as the evergreen Foxbat – come along to Hangar 11 and say hello – we are just across the grass to the south of the main club house.