G-ASYP Stories - Control Jam

In the spring of 1998, the aircraft looked rather tired and HFG decided to respray it. Upon it's return all was well for a few flights, but it was noted that the control column squeaked and juddered a lot when moved.

Around this time, Dave Milne was converting to civilian flying and although he had completed the syllabus, he was short of Dual flying time for the issue of his license. After some chewing of the fat, it was decided that he would fly with Andy and see exactly how high 'YP would fly. Having heard in my youth that a Cessna 150 will climb higher than the heater, I suggested that we dress up well as although it was tee-shirt weather on the ground, at a lapse rate or 3 degrees per thousand feet it was going to be cold.

After take off, we departed to the north, the master plan being to climb in the straight line to the north and then descend in a straight line to the south, hopefully ending up back at the roughly the same place.

At first, all went well, but at full power the engine started to warm up and by 7000', the oil temperature was at the bottom of the red. We levelled off for a few minutes to allow it to stabilise. In retrospect, we allowed it to cool for a little too long and it thereafter remained a little on the low side for the remainder of the climb. Anyone familiar with the climb performance of 'YP will know that the rate of climb was in the region of 100 to 200 feet per minute above about 5000' amsl.

Having time on our hands, we started debating the symptoms of hypoxia and started looking for them.

By 1000' as 'YP continued to climb, we were debating how high we could legally fly. We finally decided that legality was outweighed by practicality as the climb speed approached the stall speed and we didn't want to investigate the stall/spin
regime at extreme altitude.

We stopped the climb at 12000'. Obviously we didn't want to thermal shock the engine on the way down and so after a leisurely 180 degree turn started a descent with a reasonable power setting, probably around 1500 RPM. It soon became apparent that although the climb had taken us well to the north of Peterborough, the descent would take us well to the south of London. More drag was required and the wing flaps extended. This improved the rate of descent such that we were down to around 6000' just to the south of Wyton and we could reduce the rate of descent, so the flaps were selected up.

The only problem was that they wouldn't go all of the way up, jamming at about 5 degrees. We both tried, but there was a problem somewhere. We decided that this was not a great problem and that a landing could still be safely made as we could still get the flaps down again.

Of course, raising the flaps changed the trim and when Dave discovered that the elevator trim had jammed we became more than a little concerned. And when the red generator warning light came on and stayed on, the situation got our full attention. Luckily our altitude enable us to get a good signal to the hand held radio at Henlow and we announced our intentions to make a no go-around approach. After switching all of the electrics off to save the battery, we spent the reminder of the descent discussing Mr Cessna's sage words on landing with a control jam, which fortuitously we had practised just a few flights earlier.

As things would have it, the remainder of the flight was uneventful and a good flapped landing was made by Dave.

Needless to say, shortly after landing all of the symptoms "went away" and we were left scratching our heads as to what had caused the problems.

The engineers were called in to investigate and discovered that when the aircraft had been repainted, the original paint had been removed by using a mixture or water and very small plastic beads. Unfortunately, the aircraft had not been fully sealed and a bead/water mixture had settled in the fuselage. This had frozen in the climb to produce the control jams. The generator warning was similarly caused by wet electrics. Things got a little complicated as to how to go about fixing the problem and there was even some talk of scrapping the aircraft. Eventually, the work was carried out by another maintenance organisation with the company that did the re-spray paying for the cost.

Last updated: 07-Oct-2005 09:06:44