Picture it, you're closing in on a annual inspection. You've already done all your checks and now it's time to work on the discrepancies. Top of the list is a leaky main landing gear. You've already taken the tire off to give some clearance to the floor in hopes of removal, however you have no luck. The next step is to break the gear over so you can pull the strut mid swing.
So, you grab a buddy to run the gear, while you watch the gear break over for that perfect sweet spot you need for a successful pull. Out of nowhere, smoke comes billowing out of the engine bay and the cockpit.
You notice the smoke in the bay but not the cockpit and tell the person running the gear to stop and turn off the master.
Simple fix right?!
Wrong!
You go to inspect for an obvious culprit and find two wires melted together, one being a fully exposed wire and the other insulated, so you take a metal free object and push the wires apart to inspect.
You think you've got it and just as you walk around to tell the buddy in the cockpit, the prop starts rotating and the smoke begins again but worse! In a panic breakers begin getting pulled and smoke continues to pour out as wires are melting left and right.
A fire extinguisher is sought after and the prop continues to rotate. Finally, we disconnect the battery in complete horror because in aircraft is still on jacks for the swing.
The prop stops. (All of this happened in a matter of minutes.)
After the burning commences, we immediately scramble to find the issue and chase the burned wires. We begin pulling panels and inspecting every nook and cranny and in sheer disappointment and fear. The issue moves all the way from under the glareshield to the main landing gear microswitches.
We immediately begin taking our steps backwards. Tracing every step we took and trying to find the moment we made a mistake. We couldn't find the answer. Every step taken to bump the gear was done correctly and no other systems were engaged.
We take a second look and then a third, and still no answers!
We dig deeper and deeper until finally, it's revealed. A screw was lodged in between the stall warning and the landing gear breaker making direct contact.
With all the other wires burned, several hot wires were now making contact. We traced each wire back beginning with landing gear and stall warning. As it is, the stall warning was connected directly to battery power thru the stater solenoid, but the missing component was a fuse.
With a bare wire and no fuse going directly to the stall warning, the stall warning system shorted to ground.
While every issue was traced back to the specific series of events, we determined none of these issues were due to our negligence. We hadn't touched any portion of the breakers nor avionics, but the impact of FOD, was impressed on us like a heavy weight.
The importance of chasing down any dropped hardware lingered. Along with that impression, was the ultimate panic thinking, what if this had happened in the air? The pilot would have no way to disonnect the battery mid flight, leading to an uncontrolled fire, with no way to stop it, and an emergency evacuation. The gravity of those thoughts, lingered; Not to mention the fact that our quick actions just saved us from a fire, unimaginable damage to ourselves, and the aircraft. Smoke inhalation alone could have been a hazard, as we were working in a small enclosed hangar that could've easily been overcome by the smoke.
In close, we had a safety meeting with our crew, explaining the cause, precautions to take when working off base and the shear value of making sure each bit of hardware is accounted for.
You never know when your mistake could lead to tragic events and preventing FOD, is of the utmost importance.
