History of Flight
On February 19, 2009, at approximately 1930 Pacific standard time, a McDonnell Douglas Helicopter 600N, registration N608BP, experienced an engine failure during cruise flight and force-landed hard on a beach in San Clemente, California. The helicopter was operated by United States Customs and Border Protection (USCBP). The airline transport pilot and commercial copilot sustained serious injuries; the passenger received minor injuries. The helicopter sustained substantial damage. Night visual meteorological conditions prevailed, and a company visual flight rules flight plan was filed. The flight departed from Long Beach Airport (Daugherty Field) at about 1900, destined for Brown Field Municipal Airport in San Diego, California.
The helicopter departed with the commercially rated pilot at the controls in the left seat. Approximately 30 minutes into the flight, at an altitude of about 1,500 feet mean sea level, the 'ECU Degrade' light illuminated on the caution panel. The airline transport pilot, seated in the right seat, assumed control. Seconds later, an "explosion" was heard from the rear, followed by multiple caution and warning panel lights. The rear-seat passenger reported hearing a sound like an engine spooling up and observed flames from the rear.
The pilot initiated an autorotation, initially aiming for a parking lot, but after observing power lines and the San Onofre Nuclear Generating Station domes, he turned 180 degrees and landed on an adjacent beach. The helicopter landed hard, semi-submerged in the surf zone. During the landing, a main rotor blade contacted and severed the tail boom; the lower fuselage and skids sustained crush damage.
Personnel Information
The 47-year-old pilot held an airline transport pilot certificate with ratings for airplane multiengine land, and a commercial pilot certificate with ratings for airplane single-engine land, helicopter, and instrument helicopter. He also held a flight instructor certificate. According to USCBP, his total flight time was 6,000 hours, with 1,370 hours in the accident helicopter make and model.
The copilot held a commercial pilot certificate with ratings for airplane single-engine land, helicopter, instrument airplane, and instrument helicopter. His total time was 1,200 hours, including 18 hours in the accident make and model.
Aircraft Information
The no tail rotor (NOTAR) helicopter, serial number RN037, was manufactured in 1998. It had accumulated 3,571 total airframe hours at the time of the accident, 74 hours after its last 100-hour inspection in October 2008. Maintenance records indicated compliance with applicable service bulletins and airworthiness directives.
The helicopter was equipped with a Rolls-Royce 250-C47M gas turbine engine mounted in the aft fuselage at a 45-degree angle. The engine and gearbox were overhauled in December 2005 and installed in May 2006. At overhaul, the engine and gearbox had 2,278.9 hours in service; at the accident, they had 778.4 hours since overhaul. The last 150-hour inspection occurred in October 2008, 98.4 flight hours prior. No maintenance involving separation of engine and gearbox had been performed since overhaul.
Engine Examination
The engine was examined at the Rolls-Royce facility in Indianapolis. Upper and lower chip detectors contained metallic chips and flakes; the gas generator and power turbine drive trains could not be rotated manually. The accessory gearbox was separated; the number two bearing retainer ring was dislodged and resting against the oil delivery tube. The number two bearing was in place but missing most of its separator cage; remaining cage fragments were found in the gearbox housing. The bearing surfaces were oil-wetted and showed heat distress. Metallurgical examination revealed extrusion deformation on bearing ring shoulders, consistent with ball excursion. Separator fragments showed fatigue fracture features. All bearing material met design specifications.
The compressor section displayed rubbing at the 'knee' area around its full circumference; the number one bearing was intact. Thermal damage was present throughout the gas path, aft of the number one nozzle, affecting turbine blades, wheels, nozzles, and vanes.
Accessory gearbox disassembly showed no significant damage to drive trains; both could be rotated by hand. Small metallic chips were present; gears and internal surfaces were oil-wetted. Residual oil was found throughout the lubrication system.
Engine logbooks indicated the number two bearing was replaced in January 2002, 1,756 hours prior, following a compressor stall/erosion event. It was not replaced during the 2005 overhaul. The overhaul manual stated that used bearings, if properly processed, can have reliability equal to new bearings.
Additional Information
As a result of this accident and other in-service wear issues related to the number two bearing, Rolls-Royce initiated a bearing redesign process for the 250-C47M engine series.