PDA

View Full Version : PA-28 Oil Cooler Brackets


Ozgrade3
29th Apr 2002, 09:53
We run a fleet of 3 Piper Warriors. In the last few months, we've had a spate of oil cooler brackets cracking. We have installed a heavier bracket, but on one aircraft, even this new heavier bracket is only lasting about 15 hrs or so.

Anyone had a similar problem, got any ideas. I don't know if it's engine vibration comming from a dodgy engine mount, or something funny with the engine.

Any ideas on te couase would be most welcome.

Tinstaafl
29th Apr 2002, 12:38
Have you been able to find any common factors? Apart from the fact they've been flying... :p

Any change to how they're operated, any particular pilot etc etc

I seem to recall that Piper use a dynafocal mount to reduce vibration. If the mounts are going or gone then this would have an adverse effect. Not sure if it would be enough to cause your problem.

Interesting that it's happening to 3 different a/c and apparently commenced within a common period.

Cyclic Hotline
29th Apr 2002, 15:37
I would recommend that you invest a little money in getting a dynamic prop balance performed on your aircraft (although this does sound more like a high-frequency vibration to me). Worn engine mounts can cause the amplification, or even generation of sympathetic frequencies.

The latest equipment will allow not only a balance, but also a vibration spectrum analysis which will identify the specific frequencies where your vibes are originating. The latest equipment will determine RPM and balance adjustments by themselves - so you are not required to have all this information in advance. With this information, you will be able to determine the source of the vibration and most likely eliminate it or balance it out.

On helicopters we have balanced and analysed everything for years. We also do the same to our fixed-wing equipment with great success. It is interesting that even the most sceptical Operators will change their minds, after the first problem is resolved and the airplane is the smoothest it has ever been!

We use the Dynamic Solutions Micro-vibe system, but there are a number of competing products out there. If you have difficulty in finding a shop that can do this work, check out your local helicopter operator, but make sure he knows how to do props.

B2N2
30th Apr 2002, 16:50
Well,to begin with Mr.Piper made it out of $2 garbage-can sheet metal.Seen cracking occur loads of times.Always teach my students to check it during preflight.Prop-balancing might be the answer,we just beefed up the bracket..