On July 1, 2005, a Robinson R22 BETA (registration N997SA) was involved in an aviation accident near Crete, IL. Investigators recorded the probable cause as: The separation of the drive belt, during cruise, leading to the puncturing of the oil cooler and subsequent fire. An additional cause was the pilot's restricted lookout during the emergency landing resulting in the hard landing. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A helicopter sustained substantial damage after an in-flight fire, hard landing, and subsequent ground fire. The pilot reported a clutch light, smoke, and low rpm, initiating an autorotation and emergency landing.
Event Narrative
The helicopter experienced an in-flight fire, hard landing, and ground fire, resulting in substantial damage. According to the pilot's accident report, the flight was proceeding normally when the clutch light illuminated. The light remained on for more than seven seconds, prompting the pilot to pull the clutch circuit breaker in an attempt to protect the remaining belt. The pilot then assumed control and began setting up for an emergency landing. Shortly thereafter, smoke appeared inside the cockpit and rapidly filled the space. At approximately 1,100 feet MSL, the low rpm light and horn activated. The pilot lowered the collective and entered autorotation. After the hard landing, the occupants exited the aircraft and observed flames rising about three feet above the area of the belts.
Findings
Post-accident examination revealed burnt pieces of the alternator and drive belts at the site. A separated section of a recovered drive belt measured approximately one foot in length. The oil dipstick showed oil only on its bottom quarter. The oil cooler was damaged on its lower and inboard surfaces along the aft edge, with the lower aft corner separated at its seam. Dark media covered the engine in the area adjacent to the oil cooler, and an oil-like media was found on the tail rotor guard and vertical stabilizer. The tailcone was burned away at its forward end. No pre-impact failures of the flight control system were identified. The landing gear exhibited downward yielding, consistent with a hard landing.