This is an excerpt from a report made to the Aviation Safety Reporting System. The narrative is written by the pilot, rather than FAA or NTSB officials. To maintain anonymity, many details, such as aircraft model or airport, are often scrubbed from the reports.
While descending into ZZZ from ZZZ1, I experienced light to moderate turbulence (nothing uncommon). While descending into ZZZ, I was a little high, so I called ZZZ2 to request a descent through their airspace into ZZZ.
Shortly after I checked in, the engine on my Van’s RV-3 quit. I immediately ran a checklist ABC, airspeed pitched to 90 KIAS, then had to quickly decide where to land. I decided to continue towards ZZZ.
I then ran some checks. First I checked mixture (full in), secondary fuel pump on, no change, then I checked throttle, no change, then I switched full tanks (left side had approximately six gallons) to right side (approximately eight gallons,) no change. I then checked ignition, with no change.
I then immediately requested priority handling. I told them I had a total engine failure and would attempt to glide to ZZZ. I was approximately five to six miles out at approximately 6,500 feet MSL.
I was able to safely glide to ZZZ and was assisted by ground personnel. No damage to myself, aircraft, or personal property.
The home base for the aircraft is ZZZ, so aircraft was towed back to hangar and the culprit to the engine out was quickly identified.
A ground wire came loose and landed itself onto the ignition switch (where both left and right ignitions attach), which caused both ignition systems to ground and, in turn, shut off ignition to engine during flight.
Approximately two weeks prior to this incident the radio (which sits above the ignition switch on the panel) was worked on and the shielding to the wire harness was rewired.
I believe it was this work that inadvertently caused the ground wire to become loose and ultimately land itself on the ignition switch and cause it to ground and shut off both ignitions simultaneously.
Primary Problem: Human Factors
ACN: 1985272
From an engineering safety standpoint, routing both controls of any critical redundant system (grounding wires for magnetos in this case) to a single switch is a poor design choice.
Most certified aircraft use a multi-position key switch to ground/ un-ground the magnetos.
The magneto end of these shielded wires have a boot over them. The short-coming is not having an insulating cover over the mag switch terminals.
The usual concern is that one of the P-lead wires will become disconnected from the switch, and having a ‘hot-mag’ at engine shutdown. This is why it is prudent to do a ‘mags-off’ check, to see that the switch shuts off both mags, before we pull the mixture to lean-cutoff.
Just wanted to say to this pilot, good job. Ran all the check lists, and remained calm (well, outwardly). And did good calculation (however done) that you could glide back to that runway.
Primary problem- human factors???
Sounds like maybe a maintenance issue
Something similar in a 1960ish Beechcraft Debonaire in the mid-1960’s. Departed from near Pittsburg, PA for Savanah, GA. No issues. Left Savanah, GA for Ft Lauderdale Executive and sun setting in an hour or two. Headed out over the water at near 5,000 ft when engine quit. Checklist actions for mixture, prop, throttle, fuel tank selection, etc with no impact. Finally, ignition switch from both to right … nothing … to left, and engine restarted. Back to Savanah. It was a wire issue on/near the magneto. Repaired and on our way a couple hours later.