# NTSB LAX02LA096: Rotorway Rotorway Exec 90, N9876D, Phoenix, AZ, February 25, 2002 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: February 25, 2002, 14:30 local (21:30 UTC) - Place: Phoenix, AZ - Coordinates: 33.276668, -112.118057 - Nearby events: https://openairdocs.org/map.md?lat=33.2767&lon=-112.1181&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report September 29, 2004 - Report: Approved by Office Director - Parties: Federal Aviation Administration - NTSB case key (mKey): 54269 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX02LA096 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/54269/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=54269 - Page: https://openairdocs.org/ntsb/LAX02LA096 ## Probable cause The student's inadvertent over control of the throttle mechanism, which resulted in the bending of the throttle mechanical stop and binding the linkage in the idle position. Also causal was the CFI's inadequate supervision. A factor in the accident was the CFI's inability to add engine power due to the bent throttle mechanism during a practice autorotation. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power(partial) - mech failure/malf, maneuvering - throttle/power control - exceeded, dual student (cause) - miscellaneous,engine - bent (cause) - supervision - inadequate, pilot in command(cfi) (contributing factor) - throttle/power control - not possible, pilot in command(cfi) (contributing factor) - Forced landing, descent - emergency - Hard landing, landing - flare/touchdown - autorotation - performed, pilot in command(cfi) - Roll over, landing - flare/touchdown - landing gear,skid assembly - collapsed ## Analysis The experimental helicopter made a hard landing following a practice autorotation and loss of engine power. During the third practice autorotation, the student informed the instructor that he was unable to reintroduce power during the autorotation recovery. The instructor took control of the helicopter and attempted to roll the throttle up; however, he found it would not rotate any further. The instructor raised the collective at 10 feet agl in an attempt to cushion the landing. The helicopter hit the ground hard, the left skid collapsed, and the helicopter rolled onto its left side. Examination of the helicopter revealed the mechanical stop for the throttle was bent causing a condition in which the engine would stay at ground idle once the throttle was rolled past over center near the ground idle position. Once the linkage was driven over center, the linkage could not be moved by the throttle control A post accident run of the engine revealed no additional anomalies. ## Factual narrative On February 25, 2002, at 1430 mountain standard time, a Rotorway Exec 90 experimental helicopter, N9876D, made a hard landing following a loss of power during cruise about 5 miles south of Phoenix, Arizona, on the Gila River Indian Reservation. The helicopter was operated by Cobb International, Inc., under the provisions of 14 CFR Part 91 as an instructional flight, and sustained substantial damage. The certified flight instructor (CFI) and student pilot were not injured. Visual meteorological conditions prevailed for the local area flight that departed the Chandler Stellar Airpark (P19), Chandler, Arizona, at 1410. The flight was scheduled to terminate at P19. A flight plan had not been filed. In the CFI's written statement, he stated that he and his student were on a training flight to practice autorotations. During the third practice autorotation from 500 feet agl, the student performed the maneuver "without problems until the aircraft was straight and level after flaring" about 30 feet agl. Attempts were made to reintroduce power without success. The CFI stated he was on the controls "lightly" with the student, when the student told the CFI he could not reintroduce power. The CFI then came fully onto the controls and attempted to roll on the throttle only to discover it would not roll any further. The collective was raised to cushion the landing at 10 feet agl; however, the aircraft made hard contact with the ground, collapsing the left skid, and rolling onto its left side. The Federal Aviation Administration Inspector, who responded to the accident site, informed the National Transportation Safety Board that the mechanical stop for the throttle was bent. He stated once the linkage is driven "over center," it can't be brought back, and it remains at ground idle. The engine was started after the accident and ran "with no problems." ## Aircraft - Registration: [N9876D](https://openairdocs.org/deregistered/N9876D-2018-07-09), registration cancelled 2018-07-09, S/N RI-5160, built 1992 (OpenAirDocs) - Reported make and model: Rotorway Rotorway Exec 90 - Registry model: [Cobb International ROTORWAY EXEC 90](https://openairdocs.org/model/cobb-international-rotorway-exec-90) (registry code 13017LC) (OpenAirDocs) - Registry engine: [Rotorway RI-600N](https://openairdocs.org/engine/rotorway-ri-600n) (registry code 55009, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: R15160 - Airframe hours: 108 - Engines: Rotorway RI-162 150 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Registered owner: Cobb International Inc. - Last inspection: 100 hour, February 22, 2002, 3 hours before - Departed: P19, Chandler, AZ - Destination: P19, Chandler, AZ ## Flight crew As NTSB recorded them. NTSB leaves out names. - Flight instructor; age 42; injuries: none; flight instructor, commercial; medical: class 2, valid medical--no waivers/lim.; last flight review February 15, 2002; seat: right; flight hours: 1,198 total, 936 in this make and model, 1,132 as pilot in command, 103 in the last 90 days, 49 in the last 30 days, 3 in the last 24 hours - Student pilot; age 57; injuries: none; student; medical: class 3, valid medical--no waivers/lim.; seat: left; flight hours: 54 total, 51 in this make and model, 13 in the last 90 days, 6 in the last 30 days, 3 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 230° at 8 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 82 °F, dew point 30 °F - Altimeter: 30.10 inHg - Observed at: PHX, 8 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 20020225003479A](https://openairdocs.org/incident/20020225003479A), Feb 25, 2002: Amtr ROTORWAYEXEC, Phoenix, AZ, No damage. (-23) The student was demonstrating autorotations (with power recovery) to the instructor pilot. The helicopter entered the third practice autorotation at… ## Other investigations on N9876D (2) 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 LAX03LA084](https://openairdocs.org/ntsb/LAX03LA084), Feb 5, 2003: Cobb International Rotorway Exec 90 (N9876D), Casa Grande, AZ, substantial damage. Probable cause: the flight instructor's failure to maintain directional control of the helicopter during the flare and landing. Factors in the accident were the failure of the secondary drive shaft and inadequate… - [NTSB LAX95LA081](https://openairdocs.org/ntsb/LAX95LA081), Jan 13, 1995: Rotorway Rotorway (N9876D), Chandler, AZ, substantial damage. Probable cause: the student pilot's improper use of the helicopter's flight controls and the instructor's inadequate supervision of the flight. ## Docket (2 files) The files NTSB released with the investigation on July 17, 2004, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=54269. 399 KB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 375 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40389609&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - FAA Inspector's Statement (item 2, .PDF, 24 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40389610&FileExtension=.PDF&FileName=FAA%20Inspector%27s%20Statement-Redacted.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.