Today I flew our club Piper Arrow for the first time since its annual inspection.
When doing my checks, I noticed that the stabiliser trim tab took less turns for full travel, than it did previously. 35 (of my) turns vs 42 previously.
This isn’t the first time this changed. In fact it seems to change every time that it goes in for an annual inspection.
Is the trim system normally disconnected and reconnected during an annual inspection? Or does something else happen during an annual that could change this?
Apart from the number of turns, nothing else out of the ordinary was noticed.
Of course it’s always possible, that the simple fact that I haven’t flown it in a few weeks means that “my” turn of the trim tab is now slightly different that previously, but I don’t think that’s the case.
No, the Stabilator trim (!) is not disconnected during the annual. Is it a t-tail or a straight tail Arrow?
But whatever, be very careful with that one. I have a Warrior since 1994, and my dad had it from 1978, and we never had that.
On a normal Annual, there is no need to disconnect a low-tailed Arrow pitch trim system – but an Annual is an inspection and that doesn’t mean that it wasn’t disconnected to be worked on for some kind of defect rectification found during the inspection.
There may have been a cable, trim barrel, bearings or pulleys changed – in theory none of them should make a difference to the number of turns from one extreme to the other.
Have you asked the engineers who carried out the Annual whether they worked on the trim system? A range of movement on the flying controls should be carried out as part of the Annual.
It has been known for the pitch trim indicator to get bent whilst the cover is removed for the inspection – it’s only a thin bit of wire. The indicator runs in a scroll on the side of the trim wheel and if that has jumped position, it can restrict the amount of trim wheel movement.
I would visually check that the actual trim tab travel is to spec.
I would not fly any aircraft where there is the slightest question over any control surface linkage or movement, not least because one cannot be sure what is causing it. A spanner left in there? I would visually inspect the system – it’s probably not too hard to get in there and have a good look.
Incidentally I would also ask the shop whether they put any lube in there and if so, exactly which lube. Been there and got the t-shirt and luckily can tell the story 
Incidentally I would also ask the shop whether they put any lube in there and if so, exactly which lube. Been there and got the t-shirt and luckily can tell the story.
One good thing that I live in a place where ground temperatures of -20°C are to be expected every winter. Using the wrong kind of lube would be quickly noticed!
While it is not usual to take the trim system apart on an annual check it is at the discretion of the certifying inspector if he/she thinks further investigation & inspection.
The large amount of travel in the system makes inspecting the cables relatively easy in situ so it is unlikely to need to break into the system just for cable inspection.
The usual reason for taking the system apart is broken cable strands and replacement of the trim jack bearings.
Or, dismantling the whole jackscrew assembly, washing off the no-name gunk somebody put in there (freezing point -3C) and replacing it with the correct stuff
it with the correct stuff
It’s called “the right stuff”, Peter.
