Last year i had the alternate air door fail on the left engine causing significant partial power loss. This week it happened on the right. This is a real problem.

Frank, These are on the check every annual checklist however, my experience is until I started asking about them and checking their adjustment - it wasn't getting done. I now check them before the engine is re-cowled at annual. At one shop, they told me I had zero squawk on the annual other than what I'd brought in. I found the alt air doors were not only adjusted improperly, they were entirely inop. Glad I looked. Hope this may help you in the future.

Thanks Pat. After the right engine alt air door broke, i had the left one worked on and replaced as well. It failed after 10 hours. I mention it because when it fails, it has partially or significantly blocked airflow and reduced power on the affected engine. You will see props go out of sync; EGT fall and fuel flow go up significantly on the affected engine. Just thinking PA30/39 pilots should be ready, and like you said, inspect this item in particular.

Frank - thanks, good to know - they are not the most robust item ...

Well it's been almost a year since discussion on alternate air door failure. It has been my intention to check these often because of a partial failure some years ago. Well after clearing customs on Friday I lined up for takeoff for the 30 second flight from FXE to Pompano, I didn't get takeoff power on the right engine and aborted, cleared and asked for a taxi back to R/W 26. Long story shortened I found my Air Door up in the air intake passage about 3" above wher it had ripped loose from the three riviet that fasten the hinge to the duct body ahead of the fuel servo. Picture attached. Annual was performed prior to my Bahamas trip only 5 engine hours ago. LESSON, more diligence on criticle components!!

Kevin,

So glad you handled it well ... reminds me of when faithful leader CPPP Instructor Zach pulled an engine on take-off roll for me - it isn't that you can't handle it but boy, sure gets your adrenalin going.

FYI. I was sweeping the hangar in the 1980s while Mom was taking Ken up for some dual one day in the twin back in IL at the Landings Condo airport. I heard the engines spool up and a moment or two later, pulled back and saw the twin pass the hangar row still on the ground and moving fast - not good. I went running towards the runway 3,141'. They got it stopped on the runway and Ken reminded me today, it was an alternate air door failure. Don't even have to be in the plane to get heart/lung exercise when the air door fails.

Glad you are OK!

Pat,
So much for the 30-1/30-whatever Service note as your plane is well out of that range. As is mine.
Guess I'll spend a little time looking closely at my alternate air doors. Thanks for the info.
Steen

We have beefed up doors and hinges on our PA30. I think there is a mod to remove the original alternate air doors and fit alternate air doors in the lid of the air filter as was done with at least some of the Seneca I's. This system is much more reliable.

Alan, I have recently had a partial engine failure on takeoff due to a broken alt door hinge. I am interested in eliminating the problem. Does anyone have details of the aircleaner lid mod. or alternatively what materials did you use to beef up the door (hinge part no or thickness)

Is there a drawing available for the aircleaner mod? Best wishes Jim Peters

Hi Jim,

I cannot answer either of your questions directly, I'm sorry. I'll do some digging.

Alan