Thanks Ed and others:

I’ve had two in-flight catastrophes now and luckily both were within gliding distance from the home runway … the first one was more severe with a Lycoming swallowing an exhaust valve; last night wasn’t as bad; I checked the power briefly – it was still available.

Further, I was running with straight water to see what if any improvement there was over 50:50 glycol/water; at the top of my climb I was surprised to see that the temperature was actually worse by about 5F.  I leveled-off and extended my downwind to see if it would cool off, engine sounded different, but I extended my crosswind as well beyond the runway about half mile then turned wide downwind for the opposite runway, engine sounded different, better head back … good thing I did …

I’ll complete the water experiment as soon as I can get the pump repaired and confirm engine is still okay.

Jeff

 

From: "Ed Anderson" <eanderson@carolina.rr.com> Subject: Re: [FlyRotary] Water pump pulley departed in-flight Date: Thu, 4 Aug 2011 09:07:22 -0400 To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>

Hi Jeff,   Isn't it amazing how much better you landings are - when you are intensely  focused {:>)..  Seriously, glad you were where you were  when it happened and got it down safely.    While I am not a fan of any flow restriction (as you know), I serious doubt the additional force required to pump against the restriction would have been anywhere close to causing the problem.  It would appear - looking at the bolts - that you might have have had the problem of loose bolts for a period of time.  This can be hard to spot on the pump pulley because as the bolts either start to elongate or back out of their holes, the pulley would probably have moved with them - in other words, with a causal visual inspection, you might not notice the problem.   Most of the force on those four bolts should be in shear as the belts force is transferred to the pulley and through the bolts to the water pump.  So it would really take a large force even to shear those small bolts - far larger than likely could be transfer by the "V" belt system - you belt would likely have slipped first. Just my $0.02 assessment.   This is the first I've heard of a water pump pulley coming off - but safety wire should provide a sufficient safety measure to prevent it from happening again.   Ed

 

 

 

My water pump pulley departed the flange in-flight last night … fortunately I was right overhead on cross wind … heard a fwaap and a buzz thought something went through the exhaust or had lost an accessory belt; scanned the gauges, water temp and pressure were building fast, I cut the throttle and headed for 06 … checked the voltmeter which showed +14V so was pretty sure at least one belt was driving the alternator … made my best landing in a long time then taxied back to the hangar. Probably should have shutdown the engine right away but didn’t and it boiled over in front of the hangar.  Of course my brother was there to see this bird fly for the first time; not exactly the demonstration I wanted.  Popped the top cowling and found the water pump pulley departed but still inside the cowling. The outer belt was turned completely inside-out, which is probably what made the buzz.

 

There are only four small bolts holding that thing in place … noticed in Haynes pictures this morning that some have four studs and four bolts … guess the studs are for adding a second pulley? – but they would also add extra drive surface area.  I think I put those bolts on with standard loctite but am not 100% certain.  Anyway now I’m wondering if my restrictor plate, loading the pump, may have contributed to more vibration or is this just coincidence …

Jeff