NTSB Identification: MIA90LA182.
The docket is stored on NTSB microfiche number 42435.
Accident occurred Tuesday, September 11, 1990 in FORT PIERCE, FL
Probable Cause Approval Date: 10/02/1992
Aircraft: HILLER OH-23C, registration: N96168
Injuries: 2 Uninjured.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

THE CFI STATED THAT HE WAS TEACHING LOW ROTOR RPM RECOVERY TECHNIQUES DURING CLIMB OUT AFTER TAKEOFF. THE STUDENT WAS TO TAKE THE CONTROLS & RECOVER THE HELICOPTER TO A 4 FT HOVER. AT 30 FT, WITH THE ROTOR RPM AT 2,900, THE STUDENT TOOK CONTROL & OPENED THE THROTTLE BUT PULLED COLLECTIVE. THE ENG RPM DROPPED BELOW 2,500. THE CFI TOOK THE CONTROLS, VERIFIED THAT THE THROTTLE WAS OPENED & LOWERED COLLECTIVE. DURING THE RUN-ON LANDING AFTER TOUCHDOWN, THE MAIN ROTOR BLADES CONTACTED THE TAIL BOOM. EXAM OF THE ENG BY A MECHANIC WITH INSPECTION AUTHORIZATION REVEALED THAT ONE OF THE PACKING SEALS WHICH SEAL THE DISTRIBUTION ZONE PIPE TO THE INLET MANIFOLD, SEPARATED FOR UNDETERMINED REASONS RESULTING IN THE PARTIAL LOSS OF ENG POWER.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

LOSS OF ENGINE POWER DUE TO SEPARATION OF THE PACKING SEAL WHICH SEALS THE DISTRIBUTION ZONE PIPE TO THE INLET MANIFOLD, FOR UNDETERMINED REASONS RESULTING IN A HARD LANDING.

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