West Melbourne, FL, USA
N74603
ROBINSON HELICOPTER R22 BETA
During takeoff, while the helicopter was about 80 to 100 feet above the ground, the clutch caution light illuminated. The light stayed lit only long enough for the pilot to notice it, and then it turned off. The clutch light illuminated once again, and the pilot felt the helicopter vibrate. The pilot initiated a descent and heard a loud “pop and grinding noise” from the rear of the helicopter as he lowered the collective. The pilot autorotated and impacted the ground in a nose-low attitude. A postaccident examination of the drive system found that the grooves in the upper sheave were worn beyond serviceable limits. The helicopter’s maintenance manual requires inspection of the sheaves prior to installation of the drive belts. An entry in the logbook states that the drive belts were removed and replaced 22.9 hours prior to the accident. Given the level of wear in the upper sheave grooves, it is unlikely that maintenance personnel inspected the sheave prior to drive belt installation.
On July 15, 2010, at 1600 eastern daylight time, a Robinson R22 Beta, N74603, received substantial damage during a hard landing near West Melbourne, Florida. The certificated private pilot and passenger were not injured. Visual Meteorological conditions prevailed and no flight plane was filed for the local flight. The helicopter was registered to Eric A Sptizer LLC, and operated by Blue Hole Helicopters Inc. under the provisions of Title 14 Code of Federal Regulations Part 91. The flight was origination at the time of the accident. According to the pilot, he took off in an area of “flat pasture.” At about 80 to 100 feet, above the ground approximately 5 seconds after takeoff, the clutch caution light illuminated. The light stayed lit “just long enough to notice it” and then extinguished. The clutch light illuminated once again, and the pilot felt the aircraft vibrate. At about this time, a witness reported seeing a belt, “approximately 4-5 feet in length, falling from the helicopter.” The pilot initiated a descent and heard a “loud pop and grinding noise from the rear of the aircraft” as he lowered the collective. The pilot stated that the engine’s rpm “went high” and the “rotor rpm continued to fall.” The nose continued to “tuck forward” and he felt that “the response with aft cyclic was limited or not at all there.” The pilot autorotated and impacted the ground in a nose low attitude. Examination of the helicopter by a Federal Aviation Administration inspector found the landing gear, main rotor blades and tailcone substantially damaged consistent with a hard landing. Further examination found that one of the V-belts had broken “with a clean break.” A section of the belt was recovered away from the main wreckage, and the remaining portion was found entangled in the other V-belt’s system. The unbroken belt was separated from its sheave and damaged by the broken belt. The FAA inspector stated that the belts were “not new” and had taken on a gray color. Examination of the helicopter by a representative from Robinson Helicopter Company found that closer examination of the drive system found one half of one V-belt (one vee) was resting on the clutch shaft, forward of the upper sheave. This vee still had a large portion of the backing material still attached to it including the area which carried the other vee. The other vee to this belt was located inside the cabin. It was found that the other vee was peeled away from the backing that remained on this vee. This vee had a partial break in it and the other vee was completely disconnected. When the vee’s were matched together, the disconnect and partial break were in different positions. The clutch actuator was disconnected at the upper support bearing mount. The surfaces of the disconnect were angular and jagged consistent with an overload fracture. It was extended to 1.7” (measured between the scissor mounting surfaces). Normal extension is 1.1 -1.4”. Maximum extension was 1.85”. An entry in the logbook states that the drive belts were removed and replaced 22.9 hours prior to the accident. It is not clear whether the same belts were reinstalled, or replaced with new belts or another set of used belts. The R22 Maintenance manual requires inspection of the sheaves prior to installation of the drive belts and cautions of the results of using an unserviceable sheave. For the upper sheave to ware from a serviceable condition down to its current condition in 22.9 hours, the aircraft would have to have been operated in very extremely sandy conditions. None of the other components appeared to have been subjected to such an environment.
Separation of the main rotor drive belts due to maintenance personnel’s failure to adequately inspect the upper drive sheave prior to installing the belts.
Source: NTSB Aviation Accident Database
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