Chris Rayner 1 Posted December 17, 2012 Share Posted December 17, 2012 I had just landed from my second flight on Sunday with my Mahers Pacer. It's a lovely model with great presence in the air and forgiving flight characteristics. Powered by a Moki 135 she is slightly overpowered for her type of airframe, but that means I fly with about 1/2 throttle most of the time, indeed, takeoff can be done on full throttle, but looks better on about 3/4. The engine vibrates quite a lot, and I have a perrenial problem with retaining cowl fixings, I usually lose one in a flying session. I was just lifting her up to put her on my flight stand for refuelling, when I noticed that the cowl screw had gone awol, again, but more significantly there was a tapering gap below the fuselage from the trailing edge of the wing. On closer inspection it was clear that the vibration from the engine had loosened the steel M5 cap screws which hold the wing, and they were about 15mm undone. they are about 40mm long, so there was plenty of thread left to hold but even so it doesn't bear thinking about what would have happened if they let go. I clearly remember tightening them up when assembling the model at the field, so they must have undone in flight. I'd had two flights of about 10 minutes each with spirited aerobatics including spins loops and rolls and a fair bit of inverted flight. Next time I commit her to the air I shall smear the bolts with thread locking compound before insertion. Perhaps nylon ones would be a better choice. Quote Link to comment Share on other sites More sharing options...
Geoff S Posted December 20, 2012 Share Posted December 20, 2012 I have a Maher's Thunderbird with a Zenoah 26 and I replaced the steel M5 wing bolts with nylon simply because nylon bolts don't easily undo like steel is likely to. I was a bit wary at first but after dozens of flights they've proved more than adequate. I've added some thin ply to avoid crushing the wing but I didn't think it was posible to tighten the steel bolts sufficently. Unfortunately on mine the T nuts are well glued in or I'd replace them wth 6mm. Geoff Edited By Geoff Sleath on 20/12/2012 17:18:11 Quote Link to comment Share on other sites More sharing options...
MikeS Posted December 20, 2012 Share Posted December 20, 2012 On my P40 and Piper Pawnee I use antivibration washers under the wing bolts. Never had a problem. Mike Quote Link to comment Share on other sites More sharing options...
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