Aviation Accident Summaries

Aviation Accident Summary LAX05LA050

Ontario, CA, USA

Aircraft #1

N130JS

Schweizer 269C

Analysis

The helicopter rolled over during an autorotation following a loss of engine power. During a practical flight test examination for a private pilot certificate, the Designated Pilot Examiner (DPE) simulated a loss of engine power by retarding the throttle to idle. The student pilot lowered the collective and was performing an autorotation to the ground. The DPE noticed loss of engine noise then detected that the engine had lost power. The student pilot unsuccessfully attempted to restart the engine. During the landing sequence, the tail rotor stinger and blades impacted the ground. As the helicopter was sliding to a stop, it veered to the left and rolled over. Examination of the aircraft systems and the engine failed to disclose any abnormality, and an engine operational run test was conducted. After the engine was started, the cockpit mounted oil pressure gauge displayed an oil pressure indication within the normal operating range, and proper operation of the electrical fuel boost pump and engine driven fuel pump were verified. Once the engine was operating at temperature, the throttle was advanced to about 2,500 rpm, at which time the magnetos were checked utilizing the cockpit mounted ignition switch. Both magnetos operated within manufacturer's specifications. The engine ran smoothly during the operational check and exhibited no unusual indications and no fuel or oil leaks. The Rotorcraft Flight Manual for the Schweizer 300C Helicopter Model 269C provides the following procedure for practice autorotations: "Split the needles by lowering the collective while maintaining throttle setting. The throttle correlation will establish a high idle rpm (approximately 2,500 rpm), which will aid in preventing the engine from loading up or stalling during recovery."

Factual Information

HISTORY OF FLIGHT On December 11, 2004, about 1250 Pacific standard time, a Schweizer 269C, N130JS, made a hard landing and rolled over after a loss of power during a private pilot examination flight near Ontario, California. Western Helicopters, Inc, was operating the helicopter under the provisions of 14 CFR Part 91. The student pilot and the Designated Pilot Examiner (DPE) were not injured; the helicopter sustained substantial damage. The personal local examination flight departed Rialto, California, about 1230. Day visual meteorological conditions prevailed, and no flight plan had been filed. The primary wreckage was at 34 degrees 00.044 minutes north latitude and 117 degrees 34.386 minutes west longitude. The DPE reported that during a flight examination for a private pilot rating, while in cruse flight about 2,200 mean sea level (msl), he simulated a loss of engine power by retarding the throttle. The student pilot lowered the collective and was performing an autorotation to the ground. The DPE noticed the loss of engine noise. He got on the controls with the student pilot and told the student pilot to try to start the engine. The engine would not start despite several attempts. The DPE realized the field they originally intended to land on was very wet and muddy. Instead, they attempted to land on a 10-foot-high dirt berm. During the flaring portion of the landing, the tail rotor stinger and blades impacted the ground. As the helicopter was sliding to a stop, it veered to the left and rolled over. TESTS AND RESEARCH Investigators from the National Transportation Safety Board, the Federal Aviation Administration (FAA), and Textron Lycoming were parties to the investigation. On December 15, 2004, the wreckage was examined by investigators at the facilities for the operator, Western Operations, Inc., Rialto, California. An initial cursory examination of the engine found no evidence of catastrophic mechanical malfunction. Engine control system continuity was established from the cockpit controls to their respective locations on the engine. The top spark plugs were removed. The spark plug electrodes remained mechanically undamaged and exhibited coloration consistent with normal operation. Although the spark plugs at the number one and three cylinders were oil soaked, the oil soaking was attributed to the engine positioning at the accident location. The combustion signatures observed at the exhaust system tail pipe displayed coloration consistent with normal operation. There was no oil residue observed in the exhaust system gas path. After the spark plugs were reinstalled, investigators conducted an engine operation check. The electric fuel boost pump was electrically energized. The cockpit mounted fuel pressure gauge displayed a fuel pressure indication within the normal operating range. After the engine was started, the cockpit mounted oil pressure gauge displayed an oil pressure indication within the normal operating range. Once the engine stabilized above idle, the electric fuel pump was de-energized; the engine continued to run smoothly. The engine driven fuel pump delivered a fuel pressure indication within the normal operating range. Once the engine was operating at temperature, the throttle was advanced to about 2500 rpm, at which time the magnetos were checked utilizing the cockpit mounted ignition switch. Both magnetos operated within manufacturer's specifications. The throttle on the pilot's collective handle was moved to the idle position, indicating about 1400 rpm on the tachometer. The mixture handle was momentarily moved to the idle cutoff (ICO) position, at which time a momentary rise in engine rpm occurred before the handle was moved out of the ICO. The engine ran smoothly during the operation check and exhibited no unusual indications and no fuel or oil leaks. The Pilot's Flight Manual for the Schweizer 300C Helicopter Model 269C as reissued on September 21, 1988, and as revised on October 24, 2001, provides the following procedure for practice autorotations: "Split the needles by lowering the collective while maintaining throttle setting. The throttle correlation will establish a high idle rpm (approximately 2,500 rpm) which will aid in preventing the engine from loading up or stalling during recovery. Conversely, when the collective is raised without increasing the throttle, the correlation is such that only minor throttle adjustments will be required to perform a smooth recovery without exceeding 3,200 rpm." ADDITIONAL INFORMATION On July 15, 2005, the Safety Board investigator-in-charge (IIC) released the wreckage to the owner's representative.

Probable Cause and Findings

a loss of engine power due to the Designated Pilot Examiner's failure to follow the flight manual procedures and directives regarding throttle settings to be used for practice autorotations.

 

Source: NTSB Aviation Accident Database

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