252 Intake Duct

[Pinecone]

Does this look correct for the duct between the cowl inlet and the turbo?  

On the back side it also feels like there is a crease that narrows the inlet that runs horizontally.

I really looks wrong. But a new one is $943. WOW.

 

[231MJ]

This is always fun to get on.  Once the sleeve is in place (up as far as you can get it) you can grab both sides it close to the top (front and back) and twist it back-n-forth and that will take the crease out.  Yours looks like it's in very good shape - I would not change it.  

[milotron]

Yeah, that looks fine. Just make sure the screw/worm drive part of the clamp clears the cowl. My clamp is kind of ovalized and the screw is on the side to stay clear of the cowl.

Mine is starting to fray on the ends, but at $1AMU, I'll make it last.

First thing I do when getting the plane back from annual is inspect this whole bit as it is very easy to install such that it falls off the NACA housing under full power. It then sucks closed, blocking off the air cleaner, triggering the alternate air duct to open on take off and promptly scaring the crap out of you. At least the first time....

 

 

 

Edited March 9, 2023 by milotron

[Z W]

Yes, it looks correct. Don't tighten too hard or you can crack the fiberglass naca duct.  A shop mysteriously had to repair ours once.  Too loose and it can slip off and you'll see that alt air light come on as milotron says.  You can also get the alt air light and decreased engine performance if the boot isn't pushed up high enough before tightening, which causes the crease you've spotted to get worse.

Just received a new boot this week to install at annual in June.  Old one is patched too many times.  Mooney makes them in batches and they are not always available, order in advance if you ever do need one.  Currently in stock, unless we got the last one.

The intake filter housing it's riveted into is thin aluminum that vibrates around and is prone to cracking on the side nearest the turbo.  Inspect carefully at annual time.  

[Pinecone]

OK, thanks.  I will try to turn it a bit and see if it straightens out.

I have not had an issue at take off, but last flight in cruise, the Alt Air light would come on for a bit, then off, then back on.

[Z W]

You could check the air filter inside the housing at the bottom of that boot.  A clogged air filter is the designed reason for the alt air to come on.

You could also check the alt air door and switch, located on top of the engine on the pilot's side.  It's connected by a scat hose to the air filter housing we've been discussing.  It's a very simple system - when that boot slips off or is closed off, the engine sucks air through the hose connected to the alt air housing.  It pulls open a metal flap and then the engine gets air from the top left inside quarter of the cowling.  There's a spring-loaded wire that controls the alt air light in the plane.  A magnet and spring hold the alt air door closed under normal operation.

You might make sure the alt air door and everything is properly clean and lubricated, if adjusting the boot and checking the filter doesn't solve the problem.

[Pinecone]

Filter was cleaned and oiled at the last annual, about 25 hours ago in December.  But Byron recommends switching to a Donaldson filter.

I will ask if the Alt Air door was checked and lubed and adjusted.

Thanks

[Will.iam]

On 3/10/2023 at 6:44 AM, Pinecone said:

Filter was cleaned and oiled at the last annual, about 25 hours ago in December.  But Byron recommends switching to a Donaldson filter.

I will ask if the Alt Air door was checked and lubed and adjusted.

Thanks

Also recycle the alternate air source control knob. I. E. Pull the alternate air source knob out while the engine is running at idle and then push it back in and the alternate air light should go out and this also helped with it coming on during flight for some reason. Simple quick easy test to try and it might just cure your intermittent in flight issue. 

[MatthiasArnold]

Also check the air gap between the magnet and the alternate air door. If the gap is to wide the magnetic flux and thus the force to keep the door closed will go down significantly..

The position of the magnet and thus the gap & force can be adjusted after loosening two screws which hold the magnet in place (at least for my O2). 
Retighten them after adjustment. 
AFAIK the service manual states a holding force. 

Best,

Matthias 

[Pinecone]

Thanks for the tips.