Leading Edge #1 Pipe & Cowl Latch Interference

[Darrel Starr]

ALERT to all Leading Edge users who have original style cowl latches, check your #1 pipe to look for interference!
I just sent the following email to Leading Edge performance@wemakeyoufly.com.
I have a Leading Edge Exhaust on my PA18 Super Cub, N18SY with a 160 hp 0-320, conical mounts. It has the standard PA18-150 cowling and original cowl door latches. The right side forward latch, we discovered, was eating into the #1 exhaust pipe. After 102 hours of use the latch had almost sawed a groove all of the way through the pipe. The wall thickness of the pipe ( at least the end going into the muffler) is 0.048 inches. The depth of the groove was 0.038 inches! Please see the attached picture. Have you heard of this problem before? We will weld the slit shut in the pipe and grind off the latch as much as we can -- do you have any other ideas? I also will post the picture and this description of my experience on Supercub.org so you might want to monitor that site and respond there also.
Darrel Starr

 

[ag-pilot]

exhaust

Darrel,

I have seen this before on a buddies plane. In his case the rubber engine mounts were totally wore out and had let the front of his engine sag enough to wear a hole right where yours is on the same side. Even if yours are good I would check to see if they are tightened properly.

If that all checks out and it didn't rub when it was installed I would look the engine mount over real close for cracks or broken tubes. Something has let the front of your engine sag.

Dave

 

[Darrel Starr]

Dave, as a matter of fact, I just changed out the rubber motor mount bushings because I had the wrong ones installed. I had the engine off the engine mount and decided that since the original rubber bushings were 5 yrs old I would replace them. They are standard conical bushings and the new ones have a 1 inch diameter on the small end. When I compared them to the old set, the old ones had only a 7/8 diameter on the small end. It turns out that back in 2005 when I ordered a set of 71032 mounts from Aircraft Spruce, they invoiced me for a set of 71032 mounts but I think they sent me a set of 60883 mounts for an 0-290 which did sag. None of these mounts have a part number molded into them so beware! Aircraft Spruce after three emails and with a copy of the original invoice reluctantly agreed to return the money for my original purchase --- then had the CHEEK to suggest that it was my fault for not checking the part I received against the Piper Drawing !!!! The amount of sag was perhaps 1/4 inch at the most out near the front of the engine so this probably was a contributor but this pipe is just too close to the latch mechanism so I just want everyone to be aware of that.
I don't know if this had anything to do with the exhaust interference yet. On reassembly with the correct engine mount bushings, the exhaust pipe weld repaired and with the latch shaved off some, I will check for clearance.
Darrel


Darrel