DEN00FA028
DEN00FA028

HISTORY OF FLIGHT

On December 15, 1999, at 1650 mountain standard time, 3 miles east of Meadow Lake Airport, Peyton, Colorado, a Hughes 369D helicopter, N5190C, entered uncontrolled flight while hovering out of ground effect and impacted the ground. The commercial pilot and his passenger were not injured and the helicopter sustained substantial damage. Visual meteorological conditions prevailed for this local area orientation flight operating under Title 14 CFR Part 91, and no flight plan was filed. The flight originated from Meadow Lake Airport at 1640.

According to the pilot, he was on an orientation flight and had a non-helicopter rated pilot in the other pilot seat. The pilot said he was approaching a hover at about 20 feet above the surface when the helicopter began turning to the right. The application of full left pedal did not stop the turn and the pilot shut down the engine and landed the helicopter while it was in a right turn. Following impact, in what the pilot described as a flat attitude with the fuselage spinning to the right, the helicopter came to rest on its right side. The pilot related to local authorities that he thought he had "lost tail rotor drive."

PERSONNEL INFORMATION

The pilot held a private pilot certificate in airplane single engine land and a commercial certificate in rotorcraft - helicopter. He held a helicopter instrument certificate. His license was issued on November 30, 1981.

According to information provided in his report of the accident, he had 9601 hours of flight time with 7,302 hours in helicopters, and 1,700 hours of instrument time, all of which was in helicopters. He had 6 hours in the accident make and model helicopter and 1 hour of pilot in command time in the accident make and model. He had flown 4 hours in the last 30 days and 2 hours in the 24 hours preceding the accident flight. He had taken a biennial flight review in a Piper PA-28 approximately 3 weeks prior to the accident.

The investigation revealed the pilot was returning to active piloting after being absent from the profession for several years. His resume provided information that he retired from the United States Army in 1994. During his flying career in the Army, he flew Bell 204 and Bell 206 helicopters. No evidence was found of flight experience between his retirement from the Army and November of 1999.

The passenger, who was occupying the right front seat, held a private pilot certificate with a rating in single engine land airplanes. He had a total of 120 hours of flight experience, 70 of which was as pilot in command. He did not have any helicopter training or experience.

AIRCRAFT INFORMATION

The accident helicopter was built in 1982, and was issued a standard airworthiness certificate on December 17, 1982. The present registration number was issued in 1994. History of the helicopter between the date of manufacture and the present registration number is unknown. The helicopter had accumulated 5,978 hours since new and a 100-hour inspection was performed on July 16, 1999, at a total accumulated airframe time of 5,919 hours.

An Allison 250C20B turboshaft engine, serial number CAE-823357F, which produced 420 shaft horsepower, powered the aircraft. Total engine time was 1,812 hours, and time since the last inspection was 90 hours.

WRECKAGE AND IMPACT INFORMATION

The aircraft color was blue and white with black main rotor blades and black and white stripped tail rotor blades. It impacted in an open field in close proximity to a radio controlled model aircraft flying facility. The facility was not active at the time of the accident.

All four main rotor blades separated from the helicopter and the tail boom was cut off at fuselage station (FS) 220.0. Both the tail boom and main rotor blades exhibited paint transfer of white, blue, and black paint.

The fuselage windscreens and support structures were separated, and buckling was present over the entire fuselage. Both skids were separated and the cross tubes were deformed to the left and forward.

The fuel system remained intact and contained approximately 50 gallons of fuel.

The power plant exhibited external crushing of the accessories due to contact with the ground. The pilot reported no engine anomalies and there was no evidence of preimpact failure or malfunction.

The engine to transmission K-Matics interconnecting drive shaft was intact as was the over-running clutch. Drive through the transmission to the main rotor system and tail rotor output pinion was confirmed. The oil cooler belt was severed by impact forces but remained within the drive housing.

The tail rotor drive shaft exhibited four overload fractures. The forward portion remained attached via the K-Matics coupling. The drive shaft exhibited rotational scarring and complete severance at FS 137.5 due to contact with the tail rotor drive shaft fairing. The drive shaft exhibited an overload fracture at FS 219 with rotational scarring present forward of the overload fracture. The 3rd overload fracture occurred approximately 16 inches aft of the drive shaft damper sleeve and coincided with the approximate location of tail boom severance. The 4th overload fracture exhibited torsional twisting and occurred at the forward end of the Bendix coupling.

The tail rotor assembly and gearbox separated from the aircraft during the accident sequence. The tail rotor drive shaft Bendix coupling fail-safe device and a portion of the fractured flexible coupling remained attached to the tail rotor gearbox input shaft. The tail rotor gearbox case exhibited multiple fractures and a section of the gearbox remained attached to the separated tail boom.

One tail rotor blade remained attached to the hub assembly. It was bent approximately 60 degrees and exhibited no rotational damage.

The second tail rotor blade separated from the hub. The pitch horn had damage from impact with a main rotor blade as evidenced by the paint transfer. Both tail rotor blade abrasion strips were intact and attached.

Flight control continuity was established. All separations provided evidence of overload separation.

TESTS AND RESEARCH

Components listed on the introduction sheet of the Boeing Helicopter materials engineering laboratory report were sent to their laboratory for analysis. The results of their component analysis are provided in their report, public docket on the accident, and provide evidence that all fractures were either overload or sudden stoppage associated with impact.

ADDITIONAL DATA/INFORMATION

The wreckage was released to the owner's representative on May 31, 2000.

Use your browsers 'back' function to return to synopsis
Return to Query Page