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M20J cowl flaps stuck


Tx_Aggie

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Took my J for a 3 hour flight to Houston last week and everything worked as it should. Once I took off from DWH headed to Alabama for a week, I couldn’t get the cowl flaps to close. About 10 hours previous I had the cowl flaps adjusted to be open an inch when closed. Now they’ll only close when I wiggle each cowl flap on the ground. However when I turn the engine on, they return to stuck open. Has this happened to anyone else before? Once I get back home I plan to have my mechanic look at it. I appreciate it. 

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Disconnect the cowl flaps one at a time and operate the control rod. The hinges do wear out and mine had been repaired before I acquired the aircraft. There is a scissor mechanism below and attached to the bottom engine mount That is a possibility, especially if some foreign material got into it. Then there is the control rod and cable. It’s a pretty simple system. 

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Disconnect the cowl flaps one at a time and operate the control rod. The hinges do wear out and mine had been repaired before I acquired the aircraft. There is a scissor mechanism below and attached to the bottom engine mount That is a possibility, especially if some foreign material got into it. Then there is the control rod and cable. It’s a pretty simple system. 

I think it’s possible to hook it up backwards, if they completely disconnected it.
I would have just adjusted the connectors that are threaded at the end of the cables. Maybe not enough to give you the inch gap you wanted, but I think you would have gotten an 1/2 inch gap.
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The older mechanical cowl flaps can open too far and the tangs on the side of the flaps can get outside of the cowling and prevent closing. This happened to me once when I had the airplane preheated at TRK and the big hose from the heater forced the flap open too far. Since you adjusted yours to be open an inch when closed (I'd try 1/2") they may now be opening too far.

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10 minutes ago, PT20J said:

The older mechanical cowl flaps can open too far and the tangs on the side of the flaps can get outside of the cowling and prevent closing. This happened to me once when I had the airplane preheated at TRK and the big hose from the heater forced the flap open too far. Since you adjusted yours to be open an inch when closed (I'd try 1/2") they may now be opening too far.

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Mine are mechanical. Why would they function when the engine is not running but once the engine starts and is idling, they lock up? I will try what you suggest regardless 

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4 hours ago, Tx_Aggie said:

Mine are mechanical. Why would they function when the engine is not running but once the engine starts and is idling, they lock up? I will try what you suggest regardless 

Have you taken off the bottom cowl to check the mechanism?  The cabin vent air hose is routed under the cowl flap hinge mechanism, and if not routed PERFECTLY, the mechanism can actually rub and fray that hose.  I actually ended up with the spiral wire hooking onto the hinge mechanism randomly, so it would bind the hinge intermittently.   Only when I opened up the cowl did I notice the actual problem.

Edited by jaylw314
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Ended up being able to drop it by Don Maxwell today. The left cowl flap wall was catching on the cowling due to a worn bracket hinge. Don’s guys replaced the bracket on both sides and filed an edge down - now I’m off to the races. Glad to have their expertise available!

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