Unintended consequences (2 anecdotes)

[FastEddieB]

In the thread on pedal blocks, and previously on external camera mounts, I've advised on caution regarding even apparently benign modifications.

 

Two anecdotes:

 

1) Decades ago I read an accident report in a magazine - "Aftermath" or something similar.

 

In any case, I think it was a Cherokee. Owner has spotted a broken exhaust clamp, and replaced it with a hose clamp that looked similar, if not identical.

 

Problem was, the actual exhaust clamp had a locater pin and was meant to be left relatively loose, allowing play in the joint. The hose clamp did not allow for that play, and it led to a fracture of the pipe near the joint, with hot exhaust gasses hitting a fuel line, a fire, and at least one unimaginably horrible death. Yikes!

 

2) In the interest of longevity, I endeavored to move my fuel pressure sensor off of its location on an engine baffle to an area with less vibration. Seen in its new location, to the right in this photo:

 

 

Simple, easy, almost idiot-proof mod, permitted since my Sky Arrow is Experimental. Hit the boost pump, no leaks, fuel pressure indication solid. Good to go!

 

Or so I thought...

 

In order to check my oil, my adjustable cooling baffle has to be in its closed position. Went to close it, and it hung up half way.

 

Turns out the screw heads from my installation were just high enough to interfere with the baffle's movement. Not a hard fix to recess them, but there you have it - unforeseen consequence. In this case limiting the movement of a non-critical control, but just imagine...

 

Finally, even grabbing the wrong washer can set the stage for internal corrosion of a bolt that would be invisible right to the point of failure.

 

Anyway, that's my story and I'm sticking to it. Anyone else have any examples of things like this?

 

Just curious!

[Tom Baker]

I added this to the pedal extension thread.

http://www.avweb.com/avwebflash/news/Pedal_Jam_Cruse_Crash_203273-1.html

[FastEddieB]

I added this to the pedal extension thread.

http://www.avweb.com...h_203273-1.html

 

Thanks.

 

Over my 35+ years of flying, I've been made aware of many such incidents, mostly through reading accident reports.

 

Simple advice...

 

[Anticept]

There's a reason that the FAA requires A&Ps in training to take TWO YEARS in a dedicated school, or THREE years in the field, to get those ratings. I cannot stress enough how much I have learned, and I still have one semester left.

 

It's also amazing how little they know about light sport. It's funny to fly in my CTLS and teach them a little bit about it.