19980713041999I

Incident · Substantial damage

FAA incident report · Hughes 369D · El Cajon, CA · July 13, 1998

Date: July 13, 1998
Place: El Cajon, CA
Airport: Gillespie Field Airport
Phase of flight: Ops On Grnd To Tkof/Rtrcrft
Operating rules: General operating rules (Part 91)
Operator: XARA
Damage: Substantial damage
Aircraft: N58377
Reported as: Hughes 369D
People aboard: 2
Fatal injuries: 0

From the FAA’s Accident/Incident Data System (AIDS), through its Aviation Safety Information Portal, as reported. The NTSB investigates accidents separately, and its record of an accident is the fuller one. The aircraft is matched to the registry by N-number and event date, checked against the reported make and model; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.

What happened

The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.

(-5)During engine runup before collective was applied, the tail rotor drive shaft broke approximately in the middle and caused the tail boom to separate from the aircraft. It was determined that the teflon surfaces of the conical bearings for the tail rotor blades had failed, or worn out, causing excessive play at the tail rotor blades. This in turn set up a vibration in the tail rotor driveshaft causing it to flex and oscillate. Eventually, the driveshaft failed.

As the FAA filed it

(-5)DURING ENGINE RUNUP BEFORE COLLECTIVE WAS APPLIED, THE TAIL ROTOR DRIVE SHAFT BROKE APPROXIMATELY IN THE MIDDLE AND CAUSED THE TAIL BOOM TO SEPARATE FROM THE AIRCRAFT. IT WAS DETERMINED THAT THE TEFLON SURFACES OF THE CONICAL BEARINGS FOR THE TAIL ROTOR BLADES HAD FAILED, OR WORN OUT, CAUSING EXCESSIVE PLAY AT THE TAIL ROTOR BLADES. THIS IN TURN SET UP A VIBRATION IN THE TAIL ROTOR DRIVESHAFT CAUSING IT TO FLEX AND OSCILLATE. EVENTUALLY, THE DRIVESHAFT FAILED.