NTSB Identification: LAX88FA032.
The docket is stored on NTSB microfiche number 40008.
Accident occurred Tuesday, November 03, 1987 in MORAGA, CA
Probable Cause Approval Date: 04/02/1996
Aircraft: ROBINSON R22A, registration: N8475A
Injuries: 2 Fatal.

NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.

THE STUDENT WAS ON A DUAL FLIGHT, REVIEWING MANEUVERS & PROCEDURES TO REVALIDATE AN EXPIRED CFI CERTIFICATE. AN EXAM OF HIS LOG REVEALED THAT ON THE LAST 2 FLIGHTS, HE OCCUPIED THE LEFT PILOT SEAT & PRACTICED TEACHING QUICK STOPS, HOVERING AUTOROTATIONS, LOW ROTOR RPM RECOVERY & THROTTLE CUTS. WITNESSES SAID THE HELICOPTER HAD BEEN WORKING THE AREA ABOUT 20 MIN NEAR A HILL TOP. THEY SAID THE HELICOPTER WAS HOVERING 'AT 400' AGL' WHEN THE ENGINE NOISE SUDDENLY 'DIED OFF' & THEN THEY HEARD A LOUD 'POP.' THEY SAW PARTS FALLING OFF THE HELICOPTER AS IT FELL. AN EXAM OF THE WRECKAGE REVEALED A MAIN ROTOR BLADE ENTERED THE LEFT SIDE OF THE COCKPIT. NO PREIMPACT SYSTEM MALFUNCTION WAS FOUND. TOXICOLOGY TESTS SHOWED A TRACE OF MARIJUANA METABOLITE IN THE INSTRUCTOR'S URINE, BUT A TOXICOLOGIST CONCLUDED THERE WAS NO 'CURRENT INFLUENCE' OF THE DRUG. A TRACE OF COCAINE METABOLITE WAS DETECTED IN THE STUDENT'S URINE. THE SAFETY BOARD FOUND THAT THERE WAS INSUFFICIENT EVIDENCE TO CONCLUDE THAT DRUGS HAD AFFECTED EITHER PILOT'S ABILITY TO OPERATE THE AIRCRAFT.

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

A DIVERGENCE OF THE MAIN ROTOR FROM ITS NORMAL PLANE OF ROTATION FOR AN UNDETERMINED REASON, WHICH RESULTED IN ROTOR CONTACT WITH THE COCKPIT AREA.

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