Alternator and Water Pump

From: Orv  (Original Message) Sent: 8/12/2004

This is a warning to all 162F builders and flyers.

Check your systems out to be sure that this condition does not exist on your helicopter.

Since I fly so many RotorWay helicopters in the course of training students in their own ships, I run across a lot of problems that otherwise would most likely go unreported. I hope that this report is helpful to others with the same wiring configuration. A recent student and I were training in his 162f when we lost both FADEC computers, both ignitions, and both fuel pumps. The instrument panel just went out as did the engine. I had always thought that the 162F had redundant wiring to all critical systems but there is a flaw in the way it is wired (I hope that this is an isolated case and not standard from the factory) and unfortunately or fortunately we found it. The problem surfaced when one of the wires in his wire harness shorted out against a piece of metal as it ran along the frame. I often see wiring strapped to the aircraft frame and emphatically suggest that the student take the time to provide proper insulated stand offs to keep all wiring away from anything that it can short against. This helicopter's wiring was well done except for the fact that it was strapped to the frame. From now on I will not fly with wiring strapped directly to the frame, we will take the time to properly route it prior to any flights.

There is one wire on the 162f that is so critical that the way it is wired allows one single short in that wire to take out the entire primary and back up engine systems.

This wire is the one that comes off the positive side of the alternator, through a 30 amp fuse, then runs along the frame up to the overhead fuse panel.  It first goes to a (30 amp)battery fuse, then to Ignition 2 fuse, loops to Ignition 1 fuse, then to then to FADEC 2 fuse, and finally loops to FADEC 1 fuse, the final loop is back up to the second battery fuse (also 30 amp).  If you look at this routing you can see what happened.

The short in this one wire blew all three 30 amp fuses which shut down all power to both FADEC computers, both ignitions, and even both fuel pumps went off.

No power could get through the 2 blown 30 amp battery fuses or the blown 30 amp alternator fuse so it was like turning off all of the switches at once, no primary system and no back-up system to take over!!!  Once we found the problem we rewired the fuse panel and provided a second 30 amp wire and fuse from the alternator to the Battery fuse. We then wired the fuse panel so that one 30 amp wire from the alternator goes to one battery fuse, then to FADEC 1 and Ignition 1 fuses. The other one goes from the alternator through it's own 30 amp fuse then to the second 30 amp battery fuse and then loops to the FADEC 2 and Ignition 2 fuses.  We separated the  systems so that any failure of one system would not pull the second system down also.  On this trip I soloed 2 more students and we had a blast except for the unexpected engine failure. The problem is now fixed on his helicopter and it is flying superbly.

 Don't let this electrical failure happen to you, check out your wiring.

 Be safe and fly happy.
 Orv Neisingh Helicopter CFI
osn@wpcs.net
www.whitedoveaviation.us