Human Factors …

I’m writing this particular entry in the spirit of sharing (well as much as I can) and in the interests of ongoing learning and how ‘human factors’ can change the way we behave …

In August I was planning a series of circuits on a reasonably nice sunny day .. can’t particularly remember the wind but it was one of those nice days to get some circuits in and perhaps some higher work.

Checked out for an initial couple of circuits and duly took off on runway 26 banking out over Corbiere lighthouse and into the downwind and a hold at Noirmont as there was something bigger on approach. A couple of holds and then, with the newly devised ATC (neat solution to slow flying aircraft) was advanced to hold over St Aubins Fort .. which then leaves me only a short curving descent to finals.

As I broke out of the numerous tight turns over Noirmont I felt some slight vibration through the stick. Nothing massive .. but definitely a little something … checked all the gauges … RPM, CHT, Pressure, EGT all looking good so wasn’t really sure if I HAD felt it or it was something …

Slightly distracted by it .. but continuing the FIRST 2 bits of the aviation adage of Aviate, Navigate, Communicate …. I pulled out of the turn and routed towards the Fort over St Aubins bay … whilst still playing with different throttle settings to see if I could narrow down what was happening …

At this point … ATC were still thinking I was coming in for a Touch and Go and into the circuit .. as I hadn’t advised of anything …. Not Good news ..

A few more orbits and I was cleared to final .. so the vibration had been in evidence for around 2-3 minutes … rolled out eased back on the throttle and things seemed to settle so I lined up for final but declared that this would b to land … still hadn’t advised anyone outside the cockpit of why .. ‘this would be to land’

On landing .. usually really short and exit first taxiway .. I taxied into the club and pulled up outside the hanger and, brakes on, tried various throttle ranges and could feel the vibration at higher revs .. still all engine settings read absolutely fine .. so shut down to investigate.

As I climbed out and walked to the front … I saw the nosecone was pretty much in bits ! First thought was that I’d hit a bird over Norimont at around 800’ when I first felt the vibration.

I immediately called the tower to advise … not really knowing HOW or WHERE it happened but at least I now knew the WHAT. A sequence of events then happened which will be mentioned in a joint talk that ATC have asked me to co present with them in November.

Suffice to say from my perspective … there are a number of ‘Human factors’ that come to play.

  • I advised ATC that I ‘thought’ I had all the bits … was that wise without a full longer time checking ?
  • Would that ‘lead’ people to assume I was correct
  • I didn’t call ATC as soon as I felt the vibration
  • Why ? ..
  • True I was more intent on flying the problem if indeed it was a problem
  • Did I feel that I didn’t want to say that the little home built was having an issue .. so a bit of pride perhaps creeping in ?
  • Did I feel that I didn’t want to upset the smooth running of the airport .. partially yes .. I felt the ‘situation’ didn’t warrant it … I didn’t feel in immediate danger .. but perhaps I should … let’s face it .. you are after all over a fair bit of sea
  • Also .. I’m not the only one affected by ME having a problem .. as the review identified
  • Should I have shared the problem with ATC immediately .. Hell yes …
  • If I’d known (what I NOW know would be their reaction .. post my de briefing) would I have behaved the same way ?
  • Their reaction would be to hit the button … get crash crews at the end of the runway … clear any approaching aircraft out of the way by go around .. this also includes, because of where I was, a fire truck scrambled from town ! I guess in case I come down and don’t make the field ….
  • knowing all that .. would I be (more) reticent to make that call and inform ATC … probably yes if I’m honest … but the answer should be a BIG FAT NO
  • Talking all this through with Jersey ATC and understanding the knock ons that came out of this was a good learning exercise (for all)
  • How would I react to being told to go around to help a sick aircraft get in … INSTANT acquiescence of course …. would everyone ..

This left a very small piece of debris on the runway … small, flat, about 2” round fibreglass…. any delay in retrieval of that is not good … advising early and letting people decide what actions to follow is the best course of action..

In the end .. this incident caused a number of knock on learnings and reviews of documentation and procedures … all of which will ultimately make all our (flying) lives safer …

Would I do things differently next time .. YES of course …

Smoke tank fit – Ver 4

So .. after a few attempts at a range of smoke oil tank securing options … Paul Hendry Smith kindly had a chat with the top LAA man Francis Donaldson and thrashed out a workable solution… cheers Paul .. and Francis 🙂

A superbly neat solution that uses standard parts from the kit as well as a really neat alloy welded tray

The brackets will be loctite 246 glued to the outer edge of the longitudinal seat rails .. about half way down the fore-aft of the smoke oil tank

They will also be riveted in place with 2 x nickel rivets .. and then a standard aircraft grade bolt will go through these to provide a saddle clamp to run a securing ratchet strap in position

The alloy base plate also has had two pins protruding below .. alloy welded in position to prevent lateral movement

Once the faces of each part are thoroughly cleaned you put one part of the F246 glue on the outer part of the seat rails and the other on the bracket … then rivet it in position

Jabiru 2200 – Documentation update

I got an update set of documentation today from SkyCraft who are the UK agents for all things Jabiru .. some is aimed at later mark engines and this is probably one of those .. but worth a look …

Browsing through some of them I noticed there was an update on cooling options using the cowls, similar to the ones that I have. They seem to fit in a slightly different way , with a front located retaining spring vs the loop one I have around the cylinder head .. And they have the same cooling pipes at the rear , pointing down onto the Mags which get hot in use. However, there was one primary difference .. which I don’t have …

The front intake holes on the cowls had 2 ram air lower ducts fitted. These look like they have the effect of

  • compressing the incoming air
  • Forcing it into the now reduced upper section of the duct
  • Pushing this (presumably) faster air over the tops of all cylinders heads
  • Preventing (pretty much all) air from ‘bleeding’ below the cylinders

This could be a useful trial update for me .. although the engine generally runs at good temps I’ve noticed 2 up and fairly full of fuel and she does get quite warm …

Bit of a wobble ….

A few months ago, on rollout from landing I felt a slight vibration through the frame … this soon stopped as the speed fell away to walking pace and nothing further ..

I had a quick pull and push of the wheel on parking up but couldn’t really feel anything so shrugged it off as a possible ‘too quick’ landing that had induced some sort of oscillation .. somewhere ….

I flew again early September with Will , no 2 son, and we flew for about an hour over the South coast and on returning to runway 08 at Jersey the slight wind on departure had become 15kt from 360’ … not ideal … on the final bit of approach .. Will said .. “you have control” … he’d done a great job crosswind crabbing to that point

In the final 100’ we entered a bit of down draft and lost about 30’ before my early application of full power pulled her out and we rounded out in ground effect .. just a smidgen too fast ..perhaps around 55 ..

The wheel wobble , shimmy returned .. and was quite pronounced .. going away when we slowed down on hangering I had a really good look and jacked up and removed the port wheel. This showed that the out wheel bearing had just started to show signs of degradation … ie the smooth black cover that circles the roller bearings was slightly uneven on one side .. the outer side.

On reflection running large, low pressure, sticky tyres on a very grippy concrete runway at Jersey for the last 3 years and a total of about 195 landings and miles of taxiing … may just be a little too much for smallish bearings .. which probably expect to be on grass most of the time

Tool for pushing bearings in

Unfortunately the earlier failure of the bearing meant that the wheel hub centre became rounded out and so needed to replace 2 centre hub shells

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