Zenith Zodiac CH601 HDS | N6271F

DTSB: The DTSB determines the Probable Cause of this accident to be an in flight mechanical failure from the amateur built aircraft that removed pitch authority from both pilot rated occupants. The aircraft elevator cable was found at the wreck site to be severed near the aft pully, an occurrence which would not have been the result of a high speed vertical impact, which would instantly load relief the entire elevator and rudder cable tension. The accident aircraft was built by the left seat pilot and completed construction and first flight on July 30, 1997. Under FAA experimental aircraft rules, there is not a requirement to use aircraft quality cables and hardware. The accident pilot constructed the aircraft in 1997. It is suspected that the original assembly used local hardware store cables and hardware, for the purposes of cost savings. At the time of cable failure, the aircraft cables had almost 1800 hours time in service, and almost 20 years since being produced. Locally obtained hardware grade cables and hardware are often produced in China and have a much lower breaking point and useful life due to the lesser quality alloys used in production. The rudder cables were found to not be breached in any way. The aircraft entered a high speed dive as a result of the failed flight control system, and was not ever observed to pull up in any way, suggesting that while both pilots tried to stop the dive, it was not possible at the time. The NTSB did not obtain or test the quality or the origin of the severed elevator cable prior to closing their investigation more than 27 months after the crash.

NTSB: The National Transportation Safety Board determines the probable cause(s) of this accident to be:
The pilot’s loss of control during the descent for reasons that could not be determined, which
resulted in a steep descent into terrain.

DTSB: The DTSB recommends that all pilots of all amateur built aircraft conduct frequent and thorough inspections of all systems crucial to pitch and roll authority in these type aircraft. The DTSB also recommends that all elevator cables of unknown origin in experimental aircraft be replaced immediately.

NTSB: NONE