# NTSB NYC02LA099: Boucher Revolution Mini 500, N54VP, Sterling, MA, June 8, 2002 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: June 8, 2002, 16:00 local (20:00 UTC) - Place: Sterling, MA - Coordinates: 42.424999, -71.791114 - Nearby events: https://openairdocs.org/map.md?lat=42.4250&lon=-71.7911&mi=10 - Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report July 23, 2003 - Report: Approved by Office Director - Parties: FAA/FSDO - NTSB case key (mKey): 54726 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=NYC02LA099 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/54726/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=54726 - Page: https://openairdocs.org/ntsb/NYC02LA099 ## Probable cause A misalignment of the rotor system drive belt, which resulted in belt chaffing, its subsequent separation, and a resultant loss of power to the rotor system. Also causal was the relatively low altitude and airspeed at which the separation occurred, which inhibited the pilot's inability to maintain a level attitude during the autorotation. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, takeoff - initial climb - rotor drive system,main rotor drive belt - chafed - maintenance,alignment - not maintained (cause) - rotor drive system,main rotor drive belt - separation - Loss of control - in flight, takeoff - initial climb - height/velocity curve - low, pilot in command (cause) - rotor rpm - not maintained - remedial action - not successful, pilot in command - In flight collision with terrain/water, emergency landing - terrain condition - ground ## Analysis The pilot hover-taxied the helicopter from its tiedown spot to a grassy area for takeoff. Upon reaching the grassy area, he initiated a takeoff, and the helicopter accelerated through effective translational lift and began to climb. About 30 feet and 25 mph, the rotor system drive belt broke. The helicopter yawed to the left, and the pilot immediately lowered the collective and applied right rudder to correct the yaw. The helicopter impacted the ground "straight ahead but tail down." The main rotor deflected downward, and a rotor blade stuck the tail boom. The helicopter's right skid collapsed, and the helicopter rolled over on its right side and caught on fire. A section of drive belt, about 46 inches in length, had "broomstraw" separations at both ends. On the toothed side of the belt, there were about 15 areas along one edge that were worn down or missing. Another section of belt, about 40 inches in length, also had broomstaw separations at both ends, although one end had considerably less. The belt was missing material its entire length, with the missing material varying between 1/2 to 3/4 the width of the belt. ## Factual narrative On June 8, 2002, about 1600 eastern daylight time, a homebuilt Revolution Mini 500 helicopter, N54VP, was destroyed in a post-impact fire, following a forced landing during an attempted takeoff at Sterling Airport (3B3), Sterling, Massachusetts. The certificated private pilot was not injured. Visual meteorological conditions prevailed, and no flight plan had been filed for the local personal flight, conducted under 14 CFR Part 91. According to the pilot, he hover-taxied the helicopter from its tiedown spot to a grassy area for takeoff. Upon reaching the grassy area, the pilot initiated the takeoff, and the helicopter accelerated through effective translational lift and began to climb. About 30 feet and 25 mph, the rotor system drive belt broke. The helicopter yawed to the left, and the pilot immediately lowered the collective and applied right rudder to correct the yaw. The helicopter impacted the ground "straight ahead but tail down." The main rotor deflected downward, and a rotor blade stuck the tail boom. The helicopter's right skid collapsed, and the helicopter rolled over on its right side and caught on fire. A certificated airframe and powerplant mechanic reported that he had seen the pilot conduct a preflight inspection and later start the helicopter's engine. The pilot performed a run-up, then the helicopter lifted off the ground and into a hover. The mechanic turned away to work on a glider, but looked up when he heard the helicopter's engine rpm rapidly increase. He then saw the helicopter's main rotor blades hit the ground and the helicopter roll over. A small fire began in the vicinity of the engine compartment (the engine was no longer running), and eventually consumed almost the entire helicopter. According to a Federal Aviation Administration (FAA) inspector, among the charred remains of the helicopter, was a separated main rotor drive belt. The belt had worn areas along both edges. The belt had been supplied with the helicopter kit, and had, along with the helicopter, accumulated 212 hours of operation. Two sections of drive belt were provided to the Safety Board for examination. One section, about 46 inches in length, had "broomstraw" separations at both ends. On the toothed side of the belt, there were about 15 areas along one edge that were worn down or missing. The other section of belt was about 40 inches in length, and also had broomstaw separations at both ends, although one end had considerably less. The belt was missing material its entire length, with the missing material varying between 1/2 to 3/4 the width of the belt. The belt part number provided by the FAA inspector was 0506. A review of the Mini-500 master parts list described part number 0506 as "Drive belt cog type 50 mm." The belt provided by the FAA inspector had a maximum continuous width of 30 mm. ## Aircraft - Registration: [N54VP](https://openairdocs.org/deregistered/N54VP-2002-09-10), registration cancelled 2002-09-10, S/N 0054, built 1997 (OpenAirDocs) - Reported make and model: Boucher Revolution Mini 500 - Registry model: [Boucher Robert E REVOLUTION MINI 500](https://openairdocs.org/model/boucher-robert-e-revolution-mini-500) (registry code 0560490) (OpenAirDocs) - Registry engine: [Bombardier ROTAX (ALL)](https://openairdocs.org/engine/bombardier-rotax-all) (registry code 09050, reciprocating) (OpenAirDocs) - Category: Helicopter, amateur-built - Serial number: 0054 - Airframe hours: 212.2 - Engines: Rotax 582 67 horsepower reciprocating - Damage: Destroyed - Fire: On-Ground - Flight: Personal, Part 91 - Registered owner: Robert E. Boucher - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Continuous airworthiness, May 31, 2002, 1.4 hours before - Departed: 3B3, Sterling, MA - Airport: 3B3, Sterling Airport ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 56; injuries: minor; private; medical: class 3, valid medical--w/ waivers/lim; last flight review July 9, 2000; seat: single; flight hours: 4,500 total, 212 in this make and model, 20 in the last 90 days, 3 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 200° at 8 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 66 °F - Altimeter: 30.26 inHg - Observed at: ORH ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 20020608012239A](https://openairdocs.org/incident/20020608012239A), Jun 8, 2002: Amtr MINI500, Sterling, MA, No damage. (.19) On June 8, 2002, about 1600 eastern daylight time, a homebuilt revolution mini 500 helicopter, N54VP, was destroyed in a post-impact fire, following a… ## Docket (3 files) The files NTSB released with the investigation on June 1, 2003, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=54726. 1.1 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 283 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40439799&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Witness Statements (item 2, .PDF, 73 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40439800&FileExtension=.PDF&FileName=Witness%20Statements-Redacted.PDF - Wreckage Photo (FAA) (item 3, .PDF, 765 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40183715&FileExtension=.PDF&FileName=Wreckage%20Photo%20(FAA)-Master.PDF From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.