Individually Owned: 150,657
Corporate Owned: 137,281
Phoenix-Deer Valley Muni Airport
Aircraft Accident/Incident Report
Phoenix, Arizona 85027
Saturday, May 31, 1997 7:05 MST
NTSB Narrative Summary Released at Completion of Accident
While inbound to an airport, the pilot transmitted 'mayday' twice, but did not state the nature of the emergency. Witnesses saw the helicopter spin 4 to 5 revolutions, then it stopped spinning & fell to the ground. Reportedly, the rotors stopped turning before ground impact. Exam of the helicopter revealed the pivot bolts & brackets for the tail rotor drive assemblies had been overtorqued, & the pivot belts had no lubrication on the bolts or associated surfaces. The tail rotor drive belt was found frayed & shredded. Both idler pulleys & their associated mountings had not been constructed or installed correctly. A tail rotor belt advisory bulletin from Rotorway advised that temperature strips be installed on the 2 tail rotor idler pulleys & the drive pulley. It required an exam of the temperature strips before & after each flight, & it cautioned that if the 170-degree dot darkened, that was an indication that a belt may be slipping or some other problem existed; & if the 180-degree dot darkened, the belts had been damaged from heat & must be replaced. Temperature dots on this helicopter indicated the temperature had exceeded 200 degrees. The owner/builder was instructed to visually check the travel of the idler pulley swing arm, condition of the drive belts, condition of the pulleys & bearings, & temperature strips during preflight inspection. Visual inspection revealed no evidence that the inspection door had ever been opened, since the original paint seal had never been broken.
NTSB Probable Cause Narrative
the owner/builder incorrectly installed the tail rotor drive pulley mounting scissors, overtorqued the pivot belts, did not perform the required maintenance lubrication of the pivot belts, and failed to perform adequate visual maintenance checks of these areas during the pre/postflight checks; the resultant overtemperature on the pulley idlers; eventual catastrophic failure of the drive belts; and the pilot's failure to maintain rotor rpm during autorotation, which resulted in loss of aircraft control and subsequent collision with the terrain.
Event Information
| Type of Event | Accident |
| Event Date | 5/31/1997 |
| Event Day of the Week | Saturday |
| Time of Event | 705 |
| Event Time Zone | Mountain Standard Time |
| Event City | PHOENIX |
| Event State | ARIZONA |
| Event Country | -- |
| Zipcode of the event site | 85027 |
| Event Date Year | 1997 |
| Event Date Month | 5 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | |
| Event Location Longitude | |
| Event Location Airport | PHOENIX-DEER VALLEY MUNI |
| Event Location Nearest Airport ID | DVT |
| Indicates whether the acc/inc occurred off or on an airport | On Airport |
| Distance from airport in statute miles | -- |
| Degrees magnetic from airport | 60 |
| Airport Elevation | 1476 |
| Weather Briefing Completeness | Unknown |
| Investigator's weather source | Weather Observation Facility |
| Time of the weather observation | 610 Mountain Standard Time |
| Direction of event from weather observation facility (degrees) | 0 |
| Weather Observation Facility ID | DVT |
| Elevation of weather observation facility | 1476 |
| Distance of event from weather observation facility (units?) | 0 |
| Time Zone of the weather observation | MST |
| Lighting Conditions | Day |
| Lowest Ceiling Height | 0 |
| Lowest Non-Ceiling Height | 0 |
| Sky/Lowest/Cloud Conditions | Clear |
| Sky Condition for Lowest Ceiling | None |
| Visibility Runway Visual Range (Feet) | 0 |
| Visibility Runway Visual Value (Statute Miles) | 0 |
| Visibility (Statute Miles) | 50 |
| Air Temperature at event time (in degrees celsius) | 27 |
| Dew Point at event time (in degress fahrenheit) | 4 |
| Wind Direction (degrees magnetic) | 60 |
| Variable Wind Indicator | Unknown |
| Wind Speed (knots) | 6 |
| Wind Velocity Indicator | Unknown |
| Wind Gust Indicator | Not Gusting |
| Wind Gust (knots) | 0 |
| Altimeter Setting at event time (in. Hg) | 29 |
| Density Altitude (feet) | -- |
| Intensity of Precipitation | Unknown |
| METAR weather report | -- |
| Event Highest Injury | Fatal |
| On Ground, Fatal Injuries | 0 |
| On Ground, Minor Injuries | 0 |
| On Ground, Serious Injuries | 0 |
| Injury Total Fatal | 1 |
| Injury Total Minor | -- |
| Injury Total None | -- |
| Injury Total Serious | -- |
| Injury Total All | 1 |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 327 |
| NTSB Notification Source | -- |
| NTSB Notification Date | May 31 1997 12:00AM |
| NTSB Notification Time | 725 |
| Fiche Number and/or location -used to find docket information | IMAGE |
| Date of most recent change to record | Dec 8 2000 12:17PM |
| User who most recently changed record | dbo |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | -- |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N176BT |
| NTSB Number | LAX97LA197 |
| Missing Aircraft Indicator | N |
| Federal Aviation Reg. Part | Part 91: General Aviation |
| Type of Flight Plan filed | None |
| Flight plan Was Activated? | -- |
| Damage | Destroyed |
| Aircraft Fire | Ground |
| Aircraft Explosion | None |
| Aircraft Manufacturer's Full Name | Rotorway |
| Aircraft Model | 162F |
| Aircraft Series Identifier | 162F |
| Aircraft Serial Number | 6144 |
| Certified Max Gross Weight | 1425 |
| Aircraft Category | Helicopter |
| Aircraft Registration Class | U.S. Registered/U.S. Soil |
| Aircraft is a homebuilt? | Yes |
| Flight Crew Seats | -- |
| Cabin Crew Seats | -- |
| Passenger Seats | -- |
| Total number of seats on the aircraft | 2 |
| Number of Engines | 1 |
| Fixed gear or retractable gear | Fixed |
| Aircraft, Type of Last Inspection | Unknown |
| Date of Last Inspection | -- |
| Airframe hours since last inspection | -- |
| Airframe Hours | -- |
| ELT Installed | No |
| ELT Activated | Unknown |
| ELT Aided Location of Event Site | Unknown |
| ELT Type | -- |
| Aircraft Owner Name | BTS AUTOMOTIVE |
| Aircraft Owner Street Address | 17633 NORTH CAVE CREEK ROAD |
| Aircraft Owner City | PHOENIX |
| Aircraft Owner State | AZ |
| Aircraft Owner Country | |
| Aircraft Owner Zipcode | 85032 |
| Operator is an individual? | -- |
| Operator Name | |
| Operator Same as Owner? | Yes |
| Operator Is Doing Business As | -- |
| Operator Address Same as Owner? | Yes |
| Operator Street Address | |
| Operator City | |
| Operator State | |
| Operator Country | |
| Operator Zip code | |
| Operator Code | |
| Owner has at least one certificate | None |
| Other Operator of large aircraft? | No |
| Certified for Part 133 or 137 Operation | Unknown |
| Operator Certificate Number | -- |
| Indicates whether an air carrier operation was scheduled or not | -- |
| Indicates Domestic or International Flight | -- |
| Operator carrying Pax/Cargo/Mail | -- |
| Type of Flying (Per_Bus / Primary) | Personal |
| Second Pilot on Board | No |
| Departure Point Same as Event | Yes |
| Departure Airport Code | DVT |
| Departure City | |
| Departure State | |
| Departure Country | |
| Departure Time | 620 |
| Departure Time Zone | MST |
| Destination Same as Local Flt | dest & departure same, accident can occur anywhere |
| Destination Airport Code | |
| Destination City | |
| Destination State | |
| Destination Country | |
| Specific Phase of Flight | Descent - uncontrolled |
| Report sent to ICAO? | -- |
| Evacuation occurred | -- |
| Date of most recent change to record | Jan 2 2001 10:34AM |
| User who most recently changed record | dbo |
| Since inspection or accident | -- |
| Event Location Runway Number and Location | 0 |
| Runway Length | -- |
| Runway Width | -- |
| Sight Seeing flight | No |
| Air Medical Flight | No |
| Medical Flight | -- |