Hi folks!
Im just putting a query out there to the brains trust. Many of you are much more experienced than I and can bring a second (and additional) opinions to my own conclusions regarding an incident over the weekend.
Here's the story. Sorry if its long but I'm including all potentially relevant details to give context
So my bird went in for its annual this weekend. Its a great aircraft but I mentioned to my LAME that the last time the wings were detached for work the control lines hadn't been accurately tensioned, so the ailerons did not appear level when the stick was centered. And to maintain wings level in the air I was flying with the stick very slightly to the left of centre. I showed him this minor issue and asked if he could adjust during the inspection. Everything else was fine.
I picked up the aircraft over the weekend. Doing my walk around I saw the ailerons appeared my level with the stick centred. But I didn't see my LAME, just took off and flew home. In the air I immediately noticed it wasn't flying quite straight. It felt like I was flying with rudder in just to keep straight. It made be wonder whether he had overcorrected the tensioning, or I was just feeling the difference because I was used to flying it as it had been before. Not sure. It was nothing dangerous, but we just seemed to be crabbing a little. Retrospectively I also recall my airspeed was rather low on the flight home.
But things got really interesting when I came into land. Landing at my place in the wet season is kinda like landing on an aircraft carrier. On the approach you are at 300ft then you are suddenly at tree top height as you fly across the edge of the escarpment (the strip is on an escarpment). Flying my approach everything seemed quite normal but checking my airspeed I saw I was at 45 knots coming onto final and as I slowed for landing this fell to 35 knots! Normally I cross the threshold at about 50 knots and land touch down at 45 knots, so 35-40 knots seemed much too low. According to the operating handbook my Rebel will fly 34 knots with full flap, but I don't want to test that at 10ft over the trees, so I put on power and went around.
My first thought was that maybe there was a headwind or something. so on my second approach I watched airspeed both on my panel and on the GPS (ground speed). Now, if the issue was a headwind ( and there was no evidence for a headwind on my windsock), surely my airspeed would read true? But both sets of data read consistently and again I was over the trees at 35 knots indicated. Again this was too slow and I was spooked and went around for a third time. I was actually worried and wondering whether i should head back to an alternate (less challenging), airfield to land at, so to figure out the problem. But then something occurred to me. On my approaches indicated at 35 knots, the landscape didn't seem to be moving any more slowly than usual. If I didn't have the instruments and flew looking outside the cockpit the 'picture' on approach looked quite normal. So I wondered if my gauge and GPS could be inaccurate (although it seems strange that both could be reading wrong by the same margin). So on my third approach I just flew like I always do, and didn't really look at the airspeed. I landed fine. I actually ballooned slightly and so it was a long landing because I subconsciously landed fast (worried about the low indicated airspeed).
So ladies and gents, what's going on? I have thought this through over and over. The aircraft incorrectly configured, crabbing and flying slow, the mysterious 'gulley winds' for which our district is famous, or somehow both my pitot steam gauge and GPS both reading incorrectly. I struggle to believe my aircraft was actually flying at 35 knots, its never flown that slow before and it didn't feel sluggish or on the point of stall. And on my final landing I actually slightly ballooned which was unlikely to occur under 40 knots. But to my knowledge the LAME didn't so anything to the airspeed indicator. Very strange indeed.
Any ideas or suggestions? Obviously I will discuss with my LAME
Cheers
Alan