Slow cruise after annual

[RobertGary1]

Did they do any gear rigging?  Could be dragging a door.

 

-Robert

[Sandman993]

That ship must be fun to land if the IAS is reading that slow...

[marooneypilot]

I had to change altitude to be at correct VFR altitude for direction. Given my location I wanted to be safe (9k feet 30 miles from a Charlie). I realize this has an effect on the validity of the tests.

They did mess with the cowl flaps and brake line on the right main, but I had them swing the gear to make sure nothing was dragging (and that wouldn't explain the discrepancy between GS and TAS).

And yes, landings are a little sporty since I'm fairly sure I'm coming in hot.

I think next test is to go do some power on/off stalls and see what the indicated shows, although I suspect the error is lessened at lower airspeeds.

[takair]

Would recommend avionics shop do a leak check of the pitot and static system and check accuracy of the airspeed. Also, does you analogue airspeed match the Aspen?  

[carusoam]

You might want to hold off on the stall sequences... that is going a bit far for what you are trying to achieve...

1) you are describing pitot static issues... which are quite ordinary... and flying doesn’t solve them...

2) showing that you have challenges in collecting data... pics of altitude changes while collecting speed data... put on your engineering/mechanic’s hat...and go see your instrument guy...

3) you can measure T/O speed and landing speed... compare to book numbers... still going a bit too far for what you are trying to achieve... use an app like CloudAhoy... take note of wind speed too...

4) Slow flight with a stall horn chirp would give a hint... but why go that far?

Have you done stall practice lately?

If it’s been a while, bring your CFI along...

This May be considered being a test pilot.  You may have shown something to be deficient...

Take a cautious approach... whatever changed, may change more, or may change again...

Make sure you stall horn is working during the preflight... they have a tendency to disappoint every now and then...

PP thoughts only, not a mechanic or CFI...

Best regards,

-a-

[Sandman993]

Humor time...

 

I have a hat that says  "Mooney, Prepare to go fast"... we need to get him a hat that says "don't look at my airspeed indicator"

[marooneypilot]

1 hour ago, takair said:

Would recommend avionics shop do a leak check of the pitot and static system and check accuracy of the airspeed. Also, does you analogue airspeed match the Aspen?  

That's my thought too. Thanks for confirming my thinking. And yeah, my analog gauge does match the aspen, and they are from the same pitot tube. 

[jlunseth]

I have had problems in the past with the adjustment of the gear at annual. I would come back each time with a different cruise speed. I asked that they check to make sure the gear doors a fully closing and they would tell me the gear closing was checked.  I asked them to check again and sure enough they weren’t. Happened a fair amount.  My current A&P seems to get it right.  

[marooneypilot]

Update on this topic, I was able to fly with another Mooney and do some airspeed indication comparisons during various phases of flight and confirm that my ASI is reading low. I’m now talking with the avionics shop that did the IFR cert about this and hoping they come to the table to resolve the problem. 

[Guest]

You can leak check your pitot system with a length of surgical tubing, a piece of electrical tape and a clothes pin.  Push the hose over the pitot tube, tape over the drain hole on the bottom of the pitot head about 1” back, pinch the end of the hose closed with clothes pin, slowly roll the hose around the clothes pin, stop rolling at 100 KTS and watch the ASI, it should not drop.  If it drops find and correct the leak and repeat until it does not drop.

Clarence