Loss of airspeed indicator on dual GI 275 install on a night takeoff in a Mooney Ovation

[alexz]

https://www.aircraftspruce.com/catalog/pspages/degroff_pitot_5_8.php

[MarkD34M]

I am also having a GI275 installed as my AI (similar vintage Ovation as OP) to remove the vacuum systems. I've been using this relatively inexpensive Dynon as a backup, even though I've had a standby vac system. I like it because it has a long lasting battery, it is portable, snaps right in and has airspeed (obviously GPS based - but a good backup reference point), and synthetic vision.  The quality is quite good from my experience and for the price, the additional redundancy is a nice to have. 

 

[skykrawler]

Its a little disingenuous to title this event 'loss of airspeed indicator ...on GI 275'.   That is not what happened and this title will get web search hits.

The OP proceeded to take off without an indication of proper flying airspeed - what he should have done was abort.  On a twin you wouldn't leave the ground until above Vmc because you would likely lose your life if an engine failed.

Strike 1 - forgot the pitot cover

Strike 2 - take off without proper airspeed indication

Strike 3 ????

 

The 23 kts in not an erroneous reading.  It is the threshold Garmin decided was a useable value from the sensor.  Air Data Computers on 'big iron' often don't indicate until above 25 or 30 kts (on the digital data bus the signal status is marked NCD - no computed data).

[jetdriven]

I have taken off with a tennis ball that our former partner used to put over the airspeed indicator and I can confirm, the airspeed comes off the peg, but then it rolls back just about the time you lift off. 

[skykrawler]

The DA-40 I flew some had a stall warning port cover that wrapped around the leading edge of the wing and stuck to the top of the wing with a suction cup.   You could see it from the cabin.

If you put a big enough flag on it you could take off and the airflow would pull the cover off