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So the bolts backed out? I am using SS allen heads bolts and they are safetly wired. I also have a serpentine belt, and the pulley, instead of being cantilevered, is more like the wheel of a modern car, and the pulley is run off of the smooth side of the serpentine belt. But, I only have one belt running the alternator and water pump.
Brian Trubee
-----Original Message-----
From: Ben Schneider <plumberben@yahoo.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Thu, Aug 4, 2011 5:14 am
Subject: [FlyRotary] Re: Water pump pulley departed in-flight
| Glad to hear it turned out well Jeff. Was there any other damage inside the cowl from the pulley projectile? Do you have a Mazda manual for that engine, and does it list a torque spec for those bolts? Looks as though the holes are elongated fairly severely, wonder how long it had been loose. How many hours were on the engine since you last had a wrench on the pulley bolts?
Keep the group posted.
Ben
--- On Thu, 8/4/11, Jeff Whaley <jwhaley@datacast.com> wrote:
From: Jeff Whaley <jwhaley@datacast.com>
Subject: [FlyRotary] Water pump pulley departed in-flight
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Date: Thursday, August 4, 2011, 6:59 AM
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
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