Individually Owned: 150,657
Corporate Owned: 137,281
Aircraft Accident/Incident Report
Hoover Dam, Arizona 86023
Monday, September 18, 2000 8:15 MST
NTSB Narrative Summary Released at Completion of Accident
The helicopter was being operated as a sightseeing flight to the Grand Canyon. The pilot reported that during cruise flight the rotor and engine noise suddenly decreased and the helicopter began a descent. During the ensuing forced landing, the helicopter landed hard. The helicopter was fabricated from an ex-military remanufactured and modified Sikorsky S-55 (UH-19D). The original radial reciprocating engine had been replaced with a Garrett Gas Turbine TPE 331 modified to a TSE 331 IOUA 511SW. It had a 6,000-hour time between overhaul. According to maintenance records dating back to July 3, 1985, the accident engine P-54083 operated in more than one Fairchild SA226 airplane in Australia, and several rotary wing S-55 aircraft during their certification in the United States. Following the accident the engine was shipped to the modifier for functional testing in a cell. The engine started and idled normally. Increasing the rpm to the certified operating specification of 101.5 percent revealed no abnormal conditions. The test propeller was moved from the start locks and increasing torque load was applied. As the torque was increased the engine responded normally until approximately 60 percent torque when the indicated engine rpm rapidly decreased and an emergency shutdown was initiated. The process was repeated through 12 cycles, during which the indicated rpm began a sudden rapid decrease when torque was increased. Test cell troubleshooting failed to identify or correct this condition. During manual rotation of the propeller following the final cycle some "slipping" was noted between the output shaft and the main rotating group. Subsequent examination of the gearbox revealed disengagement of the sun and bull gear assembly. Examination revealed fretting damage to the retaining nut and mating surfaces related to loss of specified torque. Visual examination of the sun and bull gears revealed severe damage to the mating splines of both gears. About 9 months before the accident the original manufacturer issued a service bulletin providing for the replacement of the affected components; the engine modifier recommended replacement of the components prior to further operation. Examination of past oil analysis samplings revealed increases of iron and magnesium over a period of time, with analysis report comments of "Alert" and "Iron Appears High."
NTSB Probable Cause Narrative
The failure of maintenance personnel to accomplish a service bulletin addressing the potential failure of engine drive gears, and the ignored oil analysis testing results that indicated an impending internal engine failure that subsequently resulted in the loss of engine drive to the main rotor during flight.
Event Information
| Type of Event | Accident |
| Event Date | 9/18/2000 |
| Event Day of the Week | Monday |
| Time of Event | 815 |
| Event Time Zone | Mountain Standard Time |
| Event City | HOOVER DAM |
| Event State | ARIZONA |
| Event Country | -- |
| Zipcode of the event site | 86023 |
| Event Date Year | 2000 |
| Event Date Month | 9 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | -- |
| Event Location Longitude | -- |
| Event Location Airport | -- |
| Event Location Nearest Airport ID | -- |
| Indicates whether the acc/inc occurred off or on an airport | Off Airport/Airstrip |
| Distance from airport in statute miles | -- |
| Degrees magnetic from airport | -- |
| Airport Elevation | -- |
| Weather Briefing Completeness | Unknown |
| Investigator's weather source | Weather Observation Facility |
| Time of the weather observation | 756 Pacific Daylight Time |
| Direction of event from weather observation facility (degrees) | 270 |
| Weather Observation Facility ID | LAS |
| Elevation of weather observation facility | 2177 |
| Distance of event from weather observation facility (units?) | 30 |
| Time Zone of the weather observation | PDT |
| Lighting Conditions | Day |
| Lowest Ceiling Height | -- |
| Lowest Non-Ceiling Height | -- |
| Sky/Lowest/Cloud Conditions | Clear |
| Sky Condition for Lowest Ceiling | None |
| Visibility Runway Visual Range (Feet) | -- |
| Visibility Runway Visual Value (Statute Miles) | -- |
| Visibility (Statute Miles) | 10 |
| Air Temperature at event time (in degrees celsius) | 29 |
| Dew Point at event time (in degress fahrenheit) | 4 |
| Wind Direction (degrees magnetic) | 20 |
| Variable Wind Indicator | Wind direction could be determined |
| Wind Speed (knots) | 8 |
| Wind Velocity Indicator | -- |
| Wind Gust Indicator | Unknown |
| Wind Gust (knots) | -- |
| Altimeter Setting at event time (in. Hg) | 29.99 |
| Density Altitude (feet) | -- |
| Intensity of Precipitation | -- |
| METAR weather report | -- |
| Event Highest Injury | Minor |
| On Ground, Fatal Injuries | 0 |
| On Ground, Minor Injuries | 0 |
| On Ground, Serious Injuries | 0 |
| Injury Total Fatal | -- |
| Injury Total Minor | 7 |
| Injury Total None | -- |
| Injury Total Serious | -- |
| Injury Total All | 7 |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 12341 |
| NTSB Notification Source | -- |
| NTSB Notification Date | Sep 18 2000 12:00AM |
| NTSB Notification Time | 943 |
| Fiche Number and/or location -used to find docket information | DMS |
| Date of most recent change to record | Oct 24 2002 3:20PM |
| User who most recently changed record | NTSB\MONR |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | -- |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N17754 |
| NTSB Number | LAX00FA342 |
| Missing Aircraft Indicator | N |
| Federal Aviation Reg. Part | Part 135: Air Taxi & Commuter |
| Type of Flight Plan filed | Company VFR |
| Flight plan Was Activated? | No |
| Damage | Substantial |
| Aircraft Fire | None |
| Aircraft Explosion | None |
| Aircraft Manufacturer's Full Name | Sikorsky/Orlando |
| Aircraft Model | S-55 |
| Aircraft Series Identifier | S-55 |
| Aircraft Serial Number | V55-398T |
| Certified Max Gross Weight | 7700 |
| Aircraft Category | Helicopter |
| Aircraft Registration Class | U.S. Registered/U.S. Soil |
| Aircraft is a homebuilt? | No |
| Flight Crew Seats | -- |
| Cabin Crew Seats | -- |
| Passenger Seats | -- |
| Total number of seats on the aircraft | 7 |
| Number of Engines | 1 |
| Fixed gear or retractable gear | Fixed |
| Aircraft, Type of Last Inspection | 100 Hour |
| Date of Last Inspection | Apr 19 2000 12:00AM |
| Airframe hours since last inspection | 91 |
| Airframe Hours | 487 |
| ELT Installed | No |
| ELT Activated | No |
| ELT Aided Location of Event Site | No |
| ELT Type | -- |
| Aircraft Owner Name | Foxtrot Inc. |
| Aircraft Owner Street Address | 12515 Willows Rd. NE Ste 200 |
| Aircraft Owner City | Kirkland |
| Aircraft Owner State | WA |
| Aircraft Owner Country | -- |
| Aircraft Owner Zipcode | 98034 |
| Operator is an individual? | No |
| Operator Name | PAPILLON HELICOPTERS INC. |
| Operator Same as Owner? | No |
| Operator Is Doing Business As | -- |
| Operator Address Same as Owner? | No |
| Operator Street Address | P.O.BOX 455/HWY 64 |
| Operator City | GRAND CANYON |
| Operator State | AZ |
| Operator Country | -- |
| Operator Zip code | 86023 |
| Operator Code | PG9A |
| Owner has at least one certificate | -- |
| Other Operator of large aircraft? | -- |
| Certified for Part 133 or 137 Operation | -- |
| Operator Certificate Number | -- |
| Indicates whether an air carrier operation was scheduled or not | Non-scheduled |
| Indicates Domestic or International Flight | Domestic |
| Operator carrying Pax/Cargo/Mail | Passenger Only |
| Type of Flying (Per_Bus / Primary) | -- |
| Second Pilot on Board | No |
| Departure Point Same as Event | No |
| Departure Airport Code | LAS |
| Departure City | LAS VEGAS |
| Departure State | NV |
| Departure Country | USA |
| Departure Time | 730 |
| Departure Time Zone | PDT |
| Destination Same as Local Flt | -- |
| Destination Airport Code | GCN |
| Destination City | GRAND CANYON |
| Destination State | AZ |
| Destination Country | USA |
| Specific Phase of Flight | Cruise |
| Report sent to ICAO? | -- |
| Evacuation occurred | No |
| Date of most recent change to record | May 11 2004 2:21PM |
| User who most recently changed record | NTSB\HAMG |
| Since inspection or accident | Time of Accident |
| Event Location Runway Number and Location | -- |
| Runway Length | -- |
| Runway Width | -- |
| Sight Seeing flight | Yes |
| Air Medical Flight | No |
| Medical Flight | -- |