I went out with my son for a few hours of RV fun over the long weekend. I did a complete preflight to include looking in the pitot tube (my plane is stored inside a hangar, but without a pitot cover). Start, taxi and run-up were normal, weather was clear, slightly gusty, 10 kts at 200. As I advanced the throttle on rwy 18, the airspeed indicator began to move and I checked the engine indications. The airplane was already airborne when I realized the airspeed indications were way low at 50 kts during the initial climb and full throttle. It was too late to abort the take off due to a 3000 ft runway. I have dual Grand Rapids screens up front (HX and HS) and a HS in back. I also have a back up 3" AS indicator. They all read about 49 kts in what should have been about 120 kts. I turned crosswind, declared that I would remain in the pattern and set up for landing immediately after take off. I made one low approach and then landed on the second time around after using the GPS ground speed, 8.5" MP and normal pattern feel to make a faster than normal (I think) wheel landing. We taxied back to the hangar and began to troubleshoot. I thought it might be a plugged pitot and diconnected the pitot tubing from the instruments and blew it back out to the pitot. We tried another take off, but aborted on the runway with the same problem. A full analysis showed a significant leak which was caused by cracks in the plastic block of my TruTrak Digiflight II VSGV. I understand that TruTrak has gone to a metal block now (my AP is 4 yrs old and has been flawless until now). I used nylon fittings and hand tightened the T fittings in the back, but they cracked at 300 hrs.
Glad it was a clear day. Not throwing stones at TruTrak - they have a great product and great support as well as a service bulletin on something, but I can't open it. This is just a data point and another thing to think about when you take your aerospace vehicle out for a spin.
Bruce "FM" Edwards
RV-8, 391FM, 300 hrs
Glad it was a clear day. Not throwing stones at TruTrak - they have a great product and great support as well as a service bulletin on something, but I can't open it. This is just a data point and another thing to think about when you take your aerospace vehicle out for a spin.
Bruce "FM" Edwards
RV-8, 391FM, 300 hrs