Aspen Airspeed Issues

[Mike A]

So when I had my GTX345 installed last year, I also had the shop do the pitot/static certification. On the first flight after getting the plane back, I immediately had an issue raising the gear and learned the airspeed sensor had failed. I flew pressing the bypass button a few times and began to realize that at times, when sitting still my Aspen would show me at between 20 and 30 kias. Upon takeoff roll and the introduction of ram air it would immediately true up with the analog airspeed indicator. Then it went away for like 6 months. Now it has returned. 
 

Any thoughts on the culprit?  My theory is that they overpressure it during the pitot check and blew the airspeed switch and damaged a diaphragm or mechanism in the Aspen. 

[carusoam]

First reaction....

The airspeed switch can be OH’d...

Oddly, that may not be the most sensitive sensor on the the pitot static system...

Second (over) reaction...

What else got crushed under the high pressure test regime?

Its not like Mooney instruments are any more sensitive than other planes...

time to re-visit the instrument shop to determine next steps...

Or go to an instrument shop that cares more...

 

Third reaction...

What can possibly fail so that the ASI on an Aspen has a reading while standing still..?

Too bad we don’t have an Aspen guy... or do we? @Andy Smith

 

Fourth reaction...

Two things on the pitot static system have issues...

Posting on MS is a great way to get started...

 

Fifth reaction..

What can be stuck inside pitot tube that holds enough pressure to seem to the Aspen like it is moving, yet not enough airspeed to release the gear..?

Inspect the pitot and see if it looks like anything funny is going on?

 

PP thoughts only... not very helpful at all... 

Best regards,

-a-

 

[Marauder]

1 hour ago, Mike A said:

So when I had my GTX345 installed last year, I also had the shop do the pitot/static certification. On the first flight after getting the plane back, I immediately had an issue raising the gear and learned the airspeed sensor had failed. I flew pressing the bypass button a few times and began to realize that at times, when sitting still my Aspen would show me at between 20 and 30 kias. Upon takeoff roll and the introduction of ram air it would immediately true up with the analog airspeed indicator. Then it went away for like 6 months. Now it has returned. 
 

Any thoughts on the culprit?  My theory is that they overpressure it during the pitot check and blew the airspeed switch and damaged a diaphragm or mechanism in the Aspen. 

Mike,

I am not sure of the exact mechanism that is used in the Aspen to measure airspeed. If it is a mechanical bellows like a normal ASI, I suspect it could have been damaged. As for the 20 to 30 KIAS that you see. I have seen airspeed while in a static position in two different scenarios. The first is I am facing the wind and it is actually blowing above 20 knots and the second is if I face the plane forward and I have a right crosswind while doing a run up. I suspect the latter is some of the prop blast hitting the pitot. In both cases I would see these periodically, not on every flight.

I would make sure you are current on your firmware. There is an outstanding AD on resets but who knows what else they add into the firmware updates. Also, if you have a second MFD 1000, you could crosscheck things by placing the second unit in reversion mode. That is how I figured out what I was seeing on the PFD was weather related.

[Baker Avionics]

1 hour ago, Mike A said:

So when I had my GTX345 installed last year, I also had the shop do the pitot/static certification. On the first flight after getting the plane back, I immediately had an issue raising the gear and learned the airspeed sensor had failed. I flew pressing the bypass button a few times and began to realize that at times, when sitting still my Aspen would show me at between 20 and 30 kias. Upon takeoff roll and the introduction of ram air it would immediately true up with the analog airspeed indicator. Then it went away for like 6 months. Now it has returned. 
 

Any thoughts on the culprit?  My theory is that they overpressure it during the pitot check and blew the airspeed switch and damaged a diaphragm or mechanism in the Aspen. 

At times this may happen and will true up as described. However, there is a Tech Note TN2017-02 that an Aspen Dealer can perform. It takes about 2 hours to perform and it calibrated the either the Airspeed or Altitude Sensor or both. We just had to perform one last week. It is a little uncommon but common enough to cause a Tech Note to be Aspen to be generated. What you are seeing however is not too abnormal if it trues up in flight. If you would like more info, let me know and I will see what I can do to help you out.