Coaching Corner… There’s always more that we can learn…

The pre-flight check

While the Association was conceived for those who built their own aircraft, a considerable number of LAA members are, like me, pilots with limited engineering knowledge. I have to admit that quite a lot of the regular monthly contents of this magazine, including much of the safety information, is above my head. There must be quite a few owners around who are in a similar situation.

Nevertheless, even if we pilots do not have much engineering expertise, we do have the responsibility to ensure our aircraft is airworthy. We should learn as much about it as possible to help us identify when it might not be. Anything out of the ordinary should be inspected. Engineers are not always available to assist, and so we tend to rely on our own knowledge and common sense to decide whether the aircraft is safe to fly on a particular day. However, even if we as pilots are content that what we have noticed will have no effect on our flight, we ought to get the advice of an engineer as soon as practicable.

I was recently reminded that, whether or not our experience and knowledge renders us capable of deciding an aircraft’s serviceability, neither are of any use if we don’t notice anything wrong! For that we need good eyes and attention to detail. At the time, I was watching a couple of engineers carrying out a 150-hour check on a fairly new aeroplane of a type which appears on the LAA register. I had been helping with whatever unskilled labour I could provide, but was keeping as far out of their way as possible during the actual inspection because, as we know, distraction can be a serious hazard.

Below Alarm bells rang when a couple of bolt threads were clearly visible in the gap during an inspection.

I had recently been flying this aeroplane quite a lot. I had carried out several daily checks, as I thought carefully, without noticing anything out of the ordinary. Certainly there had been nothing to suggest any unserviceability, and as a group we had always emphasised the importance of keeping the aircraft clean, so one would have expected any abnormality to have been obvious during the pilot’s daily pre-flight inspection.

This 150-hour inspection procedure started with the removal of a number of external panels, after which I took the opportunity to improve my understanding of the aircraft by seeing where and how the controls were connected, and where various other systems were positioned. However, it was not the hidden systems which caused one of the engineers to catch his breath. He was inspecting the undercarriage mountings underneath the aircraft, which were always visible during a pre-flight inspection. Looking from the front, he had noticed that the gap at the mounting bolt between the fuselage structure and the undercarriage leg on the port side was slightly different from the gap on the starboard side, as if there were more washers around the bolt. Although he had carried out several recent pre-flight inspections himself, he had not noticed the difference during these, and he berated himself for that fact.

So what was important about that difference in the size of the gap? It indicated that the bolt itself was not fully tight. In fact, as can be seen, on closer inspection a couple of bolt threads were actually visible in the gap.

Moreover, as the investigation continued, it became apparent that of the four bolts which were used to hold the undercarriage to the fuselage, three were loose enough to turn with finger pressure. This should of course should not have been allowed to happen, and a suitable engineering solution was implemented to prevent it happening again, hopefully with a report to the LAA, which could be distributed to warn other users of the same type. However, as a pilot, the incident reminded me that any slight inconsistency visible on the pre-flight inspection could well be a warning of a future problem, and that I should be a lot more conscientious with my pre-flight checks.

Magnetic or true?

Readers may be aware that the position of the North Magnetic Pole is changing increasingly rapidly. Several articles in scientific and aviation journals have appeared, suggesting that the world of aviation should stop using the Magnetic Poles as its primary reference, and consider all its directions relative to True North. That would be quite a change. Most of us have got used to our sole means of heading reference being a magnetic compass. For all its faults, it fits the VFR flight legal requirement for ‘a means of indicating magnetic heading’, while being relatively inexpensive.

Traditional pre-flight navigation planning is carried out on charts with reference to True North, and headings are only converted to Magnetic at the final stage so that we can use our compass, or a gyro aligned with it, to set and maintain them in flight. However, as an instructor I know that student (and other) pilots frequently struggle with the variation and deviation which we have to apply during that planning stage, even if (or perhaps because), at the moment we have the advantage that variation over most of mainland UK is less than two degrees.

Most of us nowadays, even technological dinosaurs like me, carry some sort of satellite navigation device, either fitted to the aircraft or ‘handheld’. Even the simplest of these devices make their initial determination of position and track (and sometimes heading) in relation to the Earth’s centre and True North. They need an internal variation compensator to display their output in relation to Magnetic North and produce an output similar to that of a compass. Most, if not all, commercial aircraft flight management systems operate on the same principle.

The CAA is concerned with airspace infringements and recommends the use of moving map displays as a means of reducing the risk. As our electronic devices become cheaper and even more widespread, it would seem quite logical to use them as our primary direction indication, and to operate using True directions rather than complicate matters by introducing possible calculation errors with variation (and deviation – a GNSS unit isn’t affected by aircraft magnetic fields).

There are, of course, pilots who will be either unable or unwilling to invest in a satnav device. For them, their current magnetic compass, with all its errors, will still be able to provide a heading reference, but in order to identify their True heading they will have to include variation and deviation. The only difference will be that if ATC ask for their heading, it will be the True heading which should be transmitted, so they should have to apply those factors before replying. However, as mentioned earlier, in the UK variation is currently a lot less than the ± 8° accuracy we can expect of a simple magnetic compass ‘in straight and unaccelerated flight’, which in any case is far from easy to maintain in typical UK weather.

Aerodrome owners would no longer have to keep repainting runway directions every time a change in magnetic variation brought them closer to a different 10° mark. Chart producers would not need to republish instrument approach and route centreline markings, or the compass roses for the VORs which remain.

Of course, any change would take time to implement, and commercial aviation will have a large say in the matter, but as I have hinted, there are many advantages for that sector, and ICAO has decided to consider the matter at the next meeting of its appropriate navigation committee.

The International Association of Institutes of Navigation believes this change should be implemented at the earliest opportunity. If you have strong views on the matter, either for or against, you might like to write to the Royal Institute of Navigation, or to the editor of this magazine with your views? Although, any decision will take time to implement, and it is not certain that ICAO will change its standards, I think we should be prepared for it, at least mentally.

Mor to strip flying

Below The CAA’s recently revised Safety Sense leaflet on strip flying. There’s an LAA Pilot Coaching course you can take, too.

April’s Coaching Corner mentioned the CAA’s SafetySense leaflet on ‘Strip Sense’, with a picture of its front cover. As sharp-eyed members will have noticed, the CAA has recently updated that particular leaflet with a different cover. The new version is not quite so comprehensive as its predecessor with regard to strip ownership, but does provide a lot of useful guidance. However, if you are new to strip flying, proper practical training is available from LAA Coaches via the Pilot Coaching Scheme Strip Flying diploma –tinyurl.com/LAAstripflyingcoaching ■

The latest LAA Engineering topics and investigations. Compiled by

Jerry Parr