# NTSB LAX94LA083: Rotorway EXEC-90, N7456T, Scottsdale, AZ, December 28, 1993 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: December 28, 1993, 11:20 local (18:20 UTC) - Place: Scottsdale, AZ - Coordinates: 33.610729, -111.889244 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=33.6107&lon=-111.8892&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed, report September 13, 1994 - Report: Approved by Office Director - NTSB case key (mKey): 28629 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX94LA083 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/28629/pdf - Page: https://openairdocs.org/ntsb/LAX94LA083 ## Probable cause A failure of the pilot-in-command to adequately conduct a preflight inspection and properly secure a fuselage cowling panel that struck a tail rotor blade, resulting in a subsequent failure of the tail rotor drive system. Factors in this accident were an in-flight separation of the cowling panel, and the inability of the pilot to effect directional control of the helicopter. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of control - in flight, cruise - fuselage,fairing - not secured (cause) - aircraft preflight - inadequate, pilot in command (cause) - fuselage,fairing - separation (contributing factor) - rotor system,tail rotor blade - foreign object damage (cause) - rotor drive system,tail rotor drive shaft - failure,total (cause) - directional control - not possible, pilot in command (contributing factor) - Forced landing, descent - emergency - Hard landing, descent - emergency ## Analysis PRIOR TO THE ACCIDENT FLIGHT, THE HELICOPTER WAS EXAMINED BY THE FAA AND ISSUED AN EXPERIMENTAL AIRWORTHINESS CERTIFICATE. THE AIRCRAFT THEN DEPARTED ON A FERRY FLIGHT OF TWO HELICOPTERS TO RETURN TO THE HELICOPTER COMPANY BUILDING. AFTER DEPARTURE, THE SECOND AIRCRAFT OBSERVED AN OBJECT GO THROUGH THE ROTOR SYSTEM OF THE ACCIDENT HELICOPTER. THE PILOT BEGAN A PRECAUTIONARY LANDING AND, SUBSEQUENTLY, EXPERIENCED AN ANTI-TORQUE SYSTEM FAILURE. AFTER TOUCHDOWN, A POSTCRASH FIRE CONSUMED 2/3 OF THE AIRCRAFT. ONE TAIL ROTOR BLADE HAD BEEN STRUCK BY A FIBERGLASS COWLING PANEL THAT WAS LATER LOCATED ALONG THE FLIGHT PATH. ## Factual narrative On December 28, 1993, about 1120 hours mountain standard time, a Rotorway Exec-90 helicopter, N7456T, crashed during a forced landing about 6 miles east of Scottsdale, Arizona. The helicopter was being operated as a visual flight rules (VFR) cross-country ferry flight to Stellar Airpark, Chandler, Arizona, when the accident occurred. The helicopter, operated by Rotorway International, was destroyed by impact and postimpact fire. The certificated commercial pilot, the sole occupant, received minor injuries. Visual meteorological conditions prevailed. The flight originated from the Scottsdale Municipal Airport about 1115 hours. The pilot reported that the helicopter was one of two aircraft being ferried back to the factory after having been inspected at the Federal Aviation Administration (FAA) Scottsdale Fight Standards District Office (FSDO). After departure, the pilot heard a "popping" sound, and the pilot of the second helicopter in the flight observed an unknown object go through the accident helicopter's rotor system. The pilot began a precautionary landing approach to an open area. During the approach, the pilot began to smell burning rubber and suspected a malfunction of the tail rotor drive belts. Several seconds later, the pilot heard and felt a "bang" and the helicopter began to spin to the left. The pilot applied right rudder pedal with no response, and attempted to control the helicopter by utilizing varying amounts of power, collective, and cyclic pitch. The helicopter descended at a high rate and struck the ground in a level attitude, collapsing the landing gear skids. After ground impact, a fire began near the engine compartment and consumed about 2/3 of the helicopter. An FAA operations inspector from the Scottsdale FSDO inspected the helicopter at the accident site. He reported that one tail rotor blade exhibited an aft crush and splitting of the leading edge of the blade at the outboard end. He also reported that a portion of a fiberglass cowling panel was located in a field, southeast of the Scottsdale airport, along the helicopters' route of flight. The panel was fragmented into several pieces and is normally attached by "dzus" fasteners to the top area of helicopter cowling. The underside of the panel exhibited "56T" written on the cowl. The helicopter had accumulated a total time in service of 612.2 flight hours. Examination of the maintenance records revealed the most recent inspection was accomplished on December 27, 1993. The accident flight was the first flight following inspection by the FAA Manufacturing Inspection Satellite Office (MISO), Scottsdale, and issuance of an experimental airworthiness certificate for the purpose of market survey. ## Aircraft - Registration: [N7456T](https://openairdocs.org/deregistered/N7456T-1997-03-04), registration cancelled 1997-03-04, S/N RI5001 (OpenAirDocs) - Reported make and model: ROTORWAY EXEC-90 - Registry model: [Cobb International ROTORWAY EXEC 90](https://openairdocs.org/model/cobb-international-rotorway-exec-90) (registry code 13017LC) (OpenAirDocs) - Category: Helicopter - Serial number: RI5001 - Airframe hours: 612 - Engines: ROTORWAY R-162 125 horsepower reciprocating - Damage: Destroyed - Fire: On-Ground - Flight: Ferry, Part 91 - Operator: Cobb International, doing business as Rotorway International - Registered owner: Cobb International - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Continuous airworthiness, December 27, 1993, 1 hours before - Destination: P19, CHANDLER, AZ ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 45; flight instructor, commercial; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; seat: left; flight hours: 1,979 total, 250 in this make and model, 1,756 as pilot in command, 108 in the last 90 days, 37 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 190° at 4 knots - Visibility: 45 statute miles - Lowest ceiling: none - Temperature: 61 °F, dew point 36 °F - Observed at: SDL, 6 nm away ## 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 19931228047329A](https://openairdocs.org/incident/19931228047329A), Dec 28, 1993: Amtr ROTORWAYEXEC, Scottsdale, AZ, Destroyed. Just out of FAA inspection on ferry flight. Cowling came off. Damaged tail rotor. Hard forced landing. Burned. ## Other investigations on N7456T (1) 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. - [NTSB LAX91LA387](https://openairdocs.org/ntsb/LAX91LA387), Sep 8, 1991: Rotorway Exec 90 (N7456T), Phoenix, AZ, substantial damage, 1 fatal. Probable cause: UNDETERMINED. 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.