The latest squawk - a defective Air Speed Indicator

by Graham Email

A few weeks ago, I decided to give Gerhard (he of Gerhard's Flying Service, McKinney TX, flying instruction to the masses) a new check-out in the Long-EZ.
I duly gave him the front seat and we took off from Sherman Municipal and headed out towards Lake Texoma. After about 10 minutes Gerhard came on the intercom:
"You have a problem with your ASI".
Sure enough, it was stuck at 105 KTIAS. When we assumed a slow flight configuration, the needle would drop below 105, but it moved erratically.
We completed the checkout maneouvers uneventfully, but then on the first landing approach, we ended up high and long on final, so declared a go-around. The second time, Gerhard touched down some way down the runway, but with Grove brakes on the plane, we stopped pretty quickly.
Gerhard then took the plane out solo. He came back 50 minutes later to report that, based on his slow flight testing, the ASI was reading at least 10 knots slow at the lower end of the speed range. He had slowed the plane nose-up to just over 50 KTIAS, and the canard had showed no signs of stalling. Normally the canard stalls ony my plane at 62 KTIAS, so this was an indication that the ASI was defective.
The ASI issue also explained why I have been floating on final and suffering long roll-outs in recent months. If the ASI is reading 10 knots low, then I would have been landing at 76 knots instead of 66 knots. That represents a lot more kinetic energy on landing, longer rollout, and more brake and tire wear. I had been noticing that the current set of tires were wearing much faster than the previous set, which lasted until sidewall deterioration led to me replacing them 3 years ago. I expected slightly greater wear on the tires due to the better brakes, but the wear rate has been quite a lot greater, to the extent that I will be replacing these tires at the next Annual.
I had the ASI tested in the plane at Lancaster by the on-field avionics shop. They confirmed that it was reading low up to 105 KTIAS, after which point it jammed. Their verdict was an internal component failure.
After taking advice about the ASI, I decided to replace it with a new ASI, since the cost of repair would be almost as high as the cost of a new ASI. This ASI had been in the plane since 1993. I have purchased a replacement ASI from Wicks with a density altitude calibration option. The new ASI was a straight swap out from the the old one, although, as is normal, the tight packaging in the nose of the plane meant some fun as we maneouvered the old and new ASIs around.
Flight testing and calibration is scheduled for Labor Day weekend.