still4given
Posts: 463
Joined: 1/27/2006
From: Victorville,
CA, USA
Status: offline
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Hi guys,
I have had my SJ50 about 6 weeks now and have been having trouble with the muffler coming loose. Initially, I had it in a Spitfire and that required a 1/2" extension to clear the fuse. I ordered one from Dub and it came with longer bolts of course. The longer bolts have a slotted head rather than the socket head bolts that come with the engine. I tightened the bolts at tightly as I could with a screwdriver. Well the muffler came loose on the very first flight. I had already done the break in on a stand using the muffler without the extension and the muffler stayed put. I did get in one flight on the Spitfire in which the muffler stayed tight.
This plane was built for our club's pylon racing and I found a better plane for this purpose, a Phoenix Strega, so I built it and transfered the SJ50 into the Strega. With the slimmer fuse of the Strega, I was able to eliminate the extension. I got out to the race on Saturday and got the plane up into the air. It was scary fast, I was jazzed! Unfortunately on my second practice lap I began to hear a slight growling sound so I landed. By the time I got the plane on the ground the engine had died and and I could see the muffler hanging by the pressure line. The rear bolt was missing and the front bolt had broken in half. I cut some new bolts to length and reinstalled it. I let it sit for a while before the races started to let the Locktite set up good.
When my heat was ready I fired it up and took off, Everything seemed fine for about half the race, I was about to lap the competition when I started loosing power. By the end of the race I was in last place. When I got the plane back to the bench I could see that the muffler had come loose again. The inside of my cowl was coated with black slime. I tried a few more times to get the muffler to stay tight but to no avail. I had to scratch from the race. Now with further inspection, I see the the hole for the rear bolt is only a little over 1/8" deep. I can only get about three turns on the bolt before it bottoms out. Is this normal? I wonder if it is possible that a small piece of bolt material had ended up in the bottom of the hole.
I plan to send the muffler to Dub for inspection and hopefully repair. I can't wait to get his new Strega in the air with some more racers. It is going to be a blast!
Blessings, Terry
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Loose muffler on my SJ50 - 
