PA-42 Cheyenne IIA
Flight Crew Instrument; Flight Crew Private; Flight Crew Multiengine
Flight Crew Last 90 Days 66; Flight Crew Total 4367; Flight Crew Type 210
Situational Awareness; Training / Qualification
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Overcame Equipment Problem
Aircraft; Procedure
I loaded the airplane.  Non-crew personnel were in and out of the airplane while on the ground. After start; I noticed an unusual audible alarm. I did not associate it with the ELT alarm. Garmin 750 would not capture satellites; so I set up flight on backup Garmin 500 which worked fine. Flight progressed normally and I was handed off from Departure to Center. On Center [frequency]; another pilot noted he heard an ELT alarm. I tuned to 121.5 and heard the ELT alarm and reported it to Center. After a few minutes; I checked my ELT and noted the arming switch had been moved to the 'On' position. I moved the switch back to 'Arm.' ELT alarm stopped and after a few minutes; the Garmin 750 captured satellites and operated normally. The airplane went into maintenance on landing and I have advised Maintenance to check the ELT battery.If you hear an ELT; check your own first. If your Garmin 750 will not capture satellites; check your ELT. The Garmin 750 in newly installed; and I am still learning it. When it behaved abnormally; I thought it was a radio problem. I should have simply reverted to basics.
PA-42 pilot; hearing reports of ELT broadcasting and noted that his GPS system would not acquire satellites; discovered that his ELT was transmitting.