Accident Overview
On May 19, 2012, about 1540 central daylight time, a Robinson R44 helicopter, registration N444WT, was substantially damaged during a forced landing after takeoff from Destin-Fort Walton Beach Airport (DTS), Destin, Florida. The certificated commercial pilot and two passengers were not injured. Visual meteorological conditions prevailed, and a company flight plan was filed for the flight. The local sightseeing flight was conducted under 14 CFR Part 91.
Pilot and Aircraft Information
The pilot held an FAA commercial pilot certificate with ratings for rotorcraft-helicopter and instrument helicopter, as well as a flight instructor certificate with similar ratings. Her most recent FAA second class medical certificate was issued March 16, 2012. She reported 433 total hours of flight experience, with 143 hours in the accident helicopter make and model.
The helicopter was manufactured in 2000 and had accrued 1,668 total aircraft hours as of the accident date. Its most recent annual inspection was completed on April 12, 2012.
Sequence of Events
According to the pilot, the helicopter had reached approximately 200 feet above ground level in the initial climb when the engine needle in the dual tachometer spiked and remained at the top of the gauge. She turned the helicopter to return to the airport, and during the turn, the low rotor rpm warning horn sounded. The pilot responded by lowering the collective control and increasing throttle, but then determined that an airport landing could not be completed due to the resultant loss of altitude.
The pilot selected a forced landing area in a sand pit and responded to another low rotor rpm alarm by again lowering the collective. She attempted to cushion the landing with available rotor rpm, but the helicopter landed hard, and the main rotor blades severed the tailboom. The helicopter came to rest upright, and the occupants egressed without injury.
In interviews provided to the local sheriff's department, the passengers each stated that the helicopter was leaning to the right during takeoff and that it beeped and descended twice before landing hard in the sand.
Engine Examination
The helicopter was examined on June 6 and 7, 2012, by FAA inspectors. The examination revealed that the engine had a stuck (open) number #5 exhaust valve caused by buildup of oil carbon deposits. According to an FAA inspector's email summary, this is an issue with Robinson Helicopters if the engine is not cooled down properly after flight. Air tour operations appear prone to carbon buildup mainly due to quick multiple shutdowns. The operator had established a post-flight cool down procedure to prevent further problems.
Manufacturer Guidance
On January 19, 1988, Textron Lycoming published Service Letter No. L197A, Recommendations to Avoid Valve Sticking. The guidance included avoiding rapid engine cool down from low power altitude changes, low power landing approach, and engine shutdown too soon after landing or ground runs.