Date: 201407
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Night
Aircraft: Dash 8-100
Operator: Air Carrier
Operating under: Part 121
Mission: Ferry / Re-Positioning
Flight phase: Takeoff / Launch
ATC / advisory: Tower ZZZ
Aircraft component: Propeller Autofeather System
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Pilot Not Flying; First Officer
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Communication Breakdown; Confusion
Second reporter function: Pilot Flying; Captain
Anomaly: Aircraft Equipment Problem Critical
Detector: Person Flight Crew
When detected: In-flight
Result: General Maintenance Action
Contributing factors: Aircraft; Human Factors; Manuals
Primary problem: Aircraft

Narrative: During our approach into ZZZ; we noticed the ARM light on the autofeather switch was illuminated with torques above 85%; without autofeather being selected. Upon reducing the Power levers below 85%; the ARM light went out. The Captain; [who] was the pilot flying; decided just to leave the power below 85% for the duration of the approach and landed safely without the ARM light being 'On'. Once on the ground; the Captain advised Maintenance Control of the [logbook] write up; and ultimately decided they would deactivate the AutoFeather System by pulling the relays and we would ferry the plane to ZZZ1. After a Maintenance Engine Run-up; ensuring the Alternate Feather System is working properly and that the AutoFeather System had been deactivated; we proceeded with the ferry flight. Before our takeoff roll; the Captain and I decided to bring the powers up near 60% torque with the autofeather being selected (autofeather selected for takeoff was a request from Maintenance Control) to ensure the ARM light would not come on before we performed our takeoff as an extra precaution. With both the power levers at near 60%; the ARM light indeed didn't come on; which led us to believe the AutoFeather System was deactivated. We shortly performed our takeoff and with power levers set for takeoff; we noticed the ARM light was illuminated again; we decided to reject the takeoff and consult with Maintenance Control about the conditions. After a joint conversation and agreement; Maintenance Control ensured us that the ARM light might come on during our takeoff roll; but would not autofeather due to the [electrical] relays being pulled. With that reassurance; we proceeded with the takeoff with the expectation that the ARM light will illuminate. We completed the flight safely with no other issue. We performed the first takeoff expecting ARM [light] would not illuminate due to deactivation; but it did. System malfunction Rejected Takeoff (RTO) to consult with Maintenance Control. [Recommend] to discuss all possibility with Maintenance Control what we can expect before performing takeoff. Part 91. Ferry flight. Non-Revenue flight.

Callback: Reporter stated Takeoff Power is approximately 90 % on the DHC-8-100 aircraft. The 'ARM' light came 'On' even with the Selector in the 'Off' position (Manual Mode) and the AutoFeather System relays de-activated. He has not heard what Maintenance might have found that was causing the 'ARM' light to illuminate.

Second narrative: July 2014. I; along with First Officer were enroute from ZZZ to ZZZ1. I was the pilot flying. About 25 to 30 miles east of ZZZ1; the autofeather 'ARM' light came on. (The autofeather was selected 'Off') The power was set at about 86 percent torque. I reduced the power below 85 percent and the light went out. I then increased the power above 85 percent again and the light came back on. My First Officer and I discussed it and we continued the flight with the power set below 85 percent and landed in ZZZ1 without incident. I contacted Dispatch and Maintenance Control and made a write-up for same. Contract Maintenance came to disable the AutoFeather System and the plan was for us to ferry the aircraft to ZZZ2. We conducted a series of tests while the Mechanic was there per Maintenance Control.My First Officer and I also discussed that before we took off that I would hold the brakes and bring the power levers up so as to see what; if anything; the autofeather ARM light would do. Upon doing so; the 'ARM' light did not come on. This seemed to match with having the AutoFeather System disabled. We were cleared for takeoff on Runway 28. As I brought the power levers up; and as the aircraft started to move; my First Officer called for the reject; and he pointed out that the ARM light had come on. Neither of us anticipated that the ARM light would come on because our belief was that the System was disabled. We cleared the runway and got permission from the Tower to park on the taxiway to contact Dispatch and Maintenance Control. Upon speaking with Maintenance; it was explained that it was possible to have the ARM light come 'On'; but that the Auto Feather System was not able to physically make either propeller feather because the relays that make that happen had been removed. We discussed this and we were satisfied with the explanation and then conducted the Ferry flight as planned. The ARM light did come on again. There was no incident with the Ferry flight. We rejected a takeoff.This rejected takeoff happened because the autofeather ARM light came on; and we were not expecting it to. We contacted Dispatch and Maintenance Control to resolve whether or not the ferry flight could be conducted safely.I don't know how data is stored by Maintenance Control for write-ups; (I would think that this one is rare as I have been here several years and had never seen it or heard of it); but if we had a way that would alert the mechanic who is talking with the flight crew about this particular write-up that let's the mechanic know to tell the flight crew that the autofeather 'ARM' light may come on; but that it cannot possibly feather either propeller because the relays that make that happen have been removed. Understand that in this instance; the Mechanic did tell us that the autofeather relays had been removed. We simply did not know that the ARM light could still come on; and once it did come on; we became unsure that it was safe to takeoff. Rejected Takeoff. Night.


Synopsis: A Captain and First Officer report about an AutoFeather 'ARM' light that illuminated on approach and later again required a Rejected Takeoff (RTO). Both pilots noted the AutoFeather System on their DHC-8-100 was selected 'OFF' during each event. The RTO was applied due to the 'ARM' light had illuminated; even though the AutoFeather System had been de-activated.