Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site oakhill.UUCP Path: utzoo!watmath!clyde!bonnie!akgua!whuxlm!harpo!decvax!genrad!wjh12!talcott!harvard!seismo!ut-sally!oakhill!oscar From: oscar@oakhill.UUCP (Oscar Strohacker) Newsgroups: net.aviation Subject: Re: Wanted: Cessna Ghostbuster Message-ID: <252@oakhill.UUCP> Date: Thu, 29-Nov-84 13:46:03 EST Article-I.D.: oakhill.252 Posted: Thu Nov 29 13:46:03 1984 Date-Received: Sun, 2-Dec-84 02:43:41 EST References: <215@ssc-vax.UUCP> Organization: Motorola Inc. Austin, Tx Lines: 36 YES, RELAYS DO FAIL or CLEAR PROP BEFORE TURNING ON MASTER SWITCH The original comment was that the power sometimes stays on with the master off, and the battery discharges. I had a 79 Cessna Aerobat 152 in which two relays ("contactors") failed in a 4 year period after it was new. Both failed in the on state. One was a starter relay and one the master relay. The parts are similar if not identical. The first time was during an annual inspection. I wasn't there to see it, but apparently the master relay failed inactivating the master switch, and the A & P created a short while working on the starter. In the time it took him to disconnect the battery, it and starter were destroyed. It cost us > $800 for a new starter, battery, two relays, labor, etc. The second time, about a year later, I was sitting in the cockpit with the window open, saying goodbye to my brother standing next to the door. I flipped on the master to check the fuel guage, and the prop started cranking just a couple of feet from him! This time it was a shorted starter relay. I sawed open one of the stuck relays with a band saw, and the copper contacts were sort of pitted and fused as if they had welded themselves together by sparking when closing. I inquired about getting the kind of relays that Cessna uses on its twins, and they were over $200 apiece. Cheap transpo, huh? oakhill!oscar Oscar Strohacker (Commercial-Inst/ASMEL) Motorola MPU Design Austin, Texas