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.

[Ragsf15e]

On 3/8/2023 at 5:49 PM, milotron said:

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....

 

 

 

Do you guys happen to know the part number for that "cloth" boot?  I don't really want to replace it at $1AMU, but mine has a tear along the upper side that is about to go past the clamp.

Also, how the heck do you not destroy these boots putting the cowling on?  It's not a fun experience!

[Ragsf15e]

Nevermind, I wasn't doing a very good job of reading the IPC.  It's 600414-001 and is indeed $1000 and out of stock...

[Z W]

2 hours ago, Ragsf15e said:

Nevermind, I wasn't doing a very good job of reading the IPC.  It's 600414-001 and is indeed $1000 and out of stock...

When I needed one a couple years ago, Maxwell was able to order it from Mooney. He direct shipped it to me, and then I put it in a box in the plane to take to him to install during annual.

I'd recommend putting your order in now. My old one had been patched, re-patched, and added on to over the years. It's a unique 252 part and can't be obtained anywhere else.

[Fix]

Mine is starting to get worn, and side (top) is nagged by some tool or something.
Still holing up good, but it wrinkles quite much, will see if I can get at better fit.

Think I bought the last one Mooney had in stock.
 

[Ragsf15e]

As far as I can tell, these are now "unobtanium".  I have called 4 MSCs and they said Mooney doesn't take orders for outside parts that they don't have in stock.  In fact Lasar told me they bought the rights from Mooney to direct purchase the vintage intake ducts from the manufacturer since Mooney wouldn't purchase them.  So this 252/Encore intake duct is not available until someone breaks the code on who makes them, gets the rights to purchase direct, and comes up with enough orders to make it feasible.

Are there ways to repair minor tears in this "cloth" boot?

[Fix]

On 3/5/2025 at 12:34 AM, Ragsf15e said:

Do you guys happen to know the part number for that "cloth" boot?  I don't really want to replace it at $1AMU, but mine has a tear along the upper side that is about to go past the clamp.

Also, how the heck do you not destroy these boots putting the cowling on?  It's not a fun experience!

I use dishwasher soap, not much.
It will work as a lube, and it will glide on way more easy!

[Z W]

17 hours ago, Ragsf15e said:

Are there ways to repair minor tears in this "cloth" boot?

My old one had been repaired with what looked like liquid firesleeve:

https://www.abthermal.com/firesleeve-open-end-liquid-dip-paste-sealant-rtv-contamination-protection.html

It might also have just been orange RTV.

It didn't look great, but may have been functional for a while. It had been worked down into the cloth material and seemed to be a decent patch.

Sorry to hear the boot has become hard to get. I did talk to the parts department directly at Mooney about it before I got mine. He told me they had some (4 I think?) in stock at the time but that I had to order it through a MSC. You could try calling them direct and see if you get a different answer today.

[Will.iam]

Also verify the short screw is in the plate hole that is closest to the boot as a normal length screw will contact the boot and start making a hole in it. The last time my cowl was off for repair the a&p was not careful and put the short screw in a different position and unfortunately put a long normal screw in there. I caught it the next time I was taking the cowl off and notice it had already started rubbing the boot. It’s now the fist thing I check when I go to pickup my Mooney after annual.

[Fix]

On 3/8/2023 at 11:19 PM, Pinecone said:

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.

Mine is also "twisted" and don't fit perfectly.
Also like yours like it's more narrow in one end restricting the airflow.

I have full power at takeoff and the Alt Air don't lit up.

This annual we done some work to make it fit better.
It got much better, but not perfect as I would like.

Will see if I can take some pictures next week.