Drifting RPM gage

[Randy Johnson]

Recently moved up to the Northshore Boston area and think Ive found paradise. Took a great flight up the Maine Coast last weekend on a stunningly beautiful day. The controller said I was the first VFR flight he had in 2014 (and it was late February!) so it must not always be nice!

Anyway, while on the way back home my RPM gauge started to drift. Even ended up in a completely 180 degree position, which is of course is off the charts. I was flying at 23 squared and so didn't touch the prop RPM while enroute. It was clearly a gauge problem and not actual high RPM. The drift happened for about a half hour, and then gradually, slowly went back to normal and operated normally for the rest of the flight.

Two points...fist I hadn't flow the aircraft for two months because of the frigid winter we have had, and secondly it was very cold outside.

Any ideas?

By the way I watched the most amazing sunset on the way back to Boston. I love my Comanche!

[Charles Schefer]

Randy,

Have you resolved this by now? I just noticed your post and see no one replied. Unfortunately I don't have any brilliant ideas for you or definitive solutions. However... given what you describe it does sound like it is gauge error. I assume that during your flight you did not hear any fluctuations in RPM? No change in harmonic nose from the prop RPM? In which case it is probably not governor related in any way (I am guessing). So if it's gauge error maybe the Tach cable needs to be replaced? You might contact somewhere like Air Parts of Lockhaven who deals with a lot of the original Piper gauges. However if you start going down the path of overhauling the gauge you might also look at a modern STC replacement like the P-1000 digital tach.

Good Luck,

- Charles

[Charles Schefer]

PS - Love the look of that yellow and red stripe paint scheme. I really like that and it looks awesome from what I see in your avatar.

[Randy Johnson]

Thanks for the comment on the paint scheme. I think its the most beautiful plane on the tarmac on any given day!

As far as the RPM gauge, it did resolve itself on the same flight. It drifted to a 180 degree position for about a half an hour and then went back to normal. Im guessing it was because I hadnt flown it all winter ... the weather in New England was very difficult this year.

[Randy Johnson]

By the way...the stripe is actually a chestnut color. I matched the new interior with that stripe color.