The Dragonfly gyroplane was in the traffic pattern at the airport in Anahuac, Texas, when witnesses saw the main rotor head separate in flight and the gyroplane subsequently hit terrain, killing the pilot.
The pilot’s friends and the mechanic who performed the last conditional inspection reported that the pilot/owner performed most of the maintenance on the gyroplane and that he had recently installed the main rotor head bearing block.
Examination of the wreckage revealed that the bearing block had been installed upside down and was being held in place solely by friction.
The NTSB determined the probable cause as the incorrect installation by the pilot, who was not a certificated mechanic or repairman, of the main rotor head bearing block, which resulted in the in-flight separation of the rotor head.
NTSB Identification: CEN14LA056
This November 2013 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.
This is a good reason to mark top and bottom on the rotor head. It will go onto the mast either direction. However, there is a captive flange on the lower side of that plank rotor head that is to take the vertical flight load. I hope the mechanic involved is not held liable for any errors committed by the owner.
Sad indeed but it puzzles me how anyone including this owner/repairman could not mistake noticing that the rotor block and thus the rotor was being held in place reportedly only by “friction” especially for such a critical part, a part that was responsible for holding the machine aloft opposing the inescapable pull of gravity. Did he not disassemble the part and notice how it was secured? The clear lesson taught by this sad experience is that we can’t assume because we think we’ve done some maintenance effort correctly that it was in fact done correctly. Quality control for the sake of safety absolutely dictates that any disassembly and reassembly of a critical part on a flying machine, be inspected by a qualified inspector when the work is finished. While I know very little about rotorcraft assembly, having been a fixed winger mostly and only flown in and operated several military helo models off and on over the years, I’m curious how the accident investigator could determine that the rotor block had been installed upside down when I assume (a key operative word) it and the rotor separated from the gyrocopter. Did he/she also assume? Hmmm
Sorry, but that should read “could mistake” leaving out the “not.”
Even though it may be an experimental or amateur built aircraft, you should have a second pair of eyes review your work.
Overall, it’s still true that about 20% of small aircraft accidents can be traced to “maintenance error”. That number is perhaps even bigger for EAB owned and maintained aircraft.
“Maintenance error?” Maintenance doesn’t make anything including errors. This was human error.
Maintenance is done by humans (most of the time). Somewhere in the line, even if it’s replacing a solid state PFD with strict adherence to ‘correct’ procedures, there is an opportunity for error. For example, the recent Honeywell auto pilot problems that resulted from a software error introduced up the chain. Human error? Probably. .