# NTSB SEA95LA227: Texas Helicopter OH-13E, N38115, Yakima, WA, September 20, 1995 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: September 20, 1995, 12:30 local (19:30 UTC) - Place: Yakima, WA - Coordinates: 46.720115, -120.410987 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=46.7201&lon=-120.4110&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report April 29, 1996 - Report: Approved by Office Director - NTSB case key (mKey): 42258 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA95LA227 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/42258/pdf - Page: https://openairdocs.org/ntsb/SEA95LA227 ## Probable cause FATIGUE FAILURE OF THE BOLT ATTACHING THE SCISSOR ARM ASSEMBLY TO THE PITCH CONTROL SUPPORT ASSEMBLY. THE FAILURE OF THE BOLT LED TO A LOSS OF COLLECTIVE PITCH CONTROL AND REDUCED ROTOR RPM. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, maneuvering - miscellaneous,bolt/nut/fastener/clamp/spring - fatigue (cause) - rotorcraft flight control,rotating scissors - disconnected (cause) - In flight collision with terrain/water, descent - uncontrolled - terrain condition - water ## Analysis IMMEDIATELY AFTER LIFTING OFF AND REACHING TRANSLATIONAL LIFT, THE PILOT LOST COLLECTIVE PITCH CONTROL AND ROTOR RPM BEGAN TO DECREASE. THE HELICOPTER BEGAN AN UNCONTROLLED DESCENT AND IMPACTED WITH A POND. EXAMINATION REVEALED THAT AN ATTACHMENT BOLT IN THE SCISSOR ARM ASSEMBLY OF THE PITCH CONTROL SUPPORT ASSEMBLY HAD FAILED. EXAMINATION OF THE FRACTURE SURFACE REVEALED THAT THE BOLT HAD FAILED IN FATIGUE, WITH MULTIPLE CRACKING ORIGINS EMANATING FROM THE THREADS OF THE BOLT. ## Factual narrative On September 20, 1995, about 1230 Pacific daylight time, N38115, a Texas Helicopter OH-13E, operated by Heli Flight Ag Service, Inc., collided with water and was substantially damaged during an uncontrolled descent into a pond near Yakima, Washington. The uncontrolled descent was precipitated by a flight control malfunction while maneuvering. The commercial pilot, the sole occupant, was not injured. Visual meteorological conditions prevailed and no flight plan had been filed. The aerial application flight departed from Yakima and was conducted under 14 CFR 137. According to an FAA aviation safety inspector from Renton, Washington, the pilot reported that one of the flight controls malfunctioned as the pilot was maneuvering. The helicopter struck a pond and sank. The pilot swam to safety. The helicopter sustained substantial damaged and was recovered. In a written statement prepared by the pilot on October 16, 1995, the pilot stated: ... during a routine spray operation I experienced a broken bolt (AN 175-33) in the scissor arm assembly on the pitch control support assembly. I had just departed from the top of a platform truck over a pond used for [irrigation] located between two orchards. Upon reaching translational lift the collective handle went full pitch. The helicopter starting hopping violently. I tried to get collective pitch down with no luck. Any collective movement only increased the hopping. With throttle wide open I started to [lose] engine and rotor RPM due to full pitch in one blade. Midway across the pond I started to descend because of low RPM. I [flared] back to stop forward airspeed and [attempted] to maintain flight. The tail rotor hit the water first with main rotors chopping tailboom assembly off. An examination of the wreckage by the FAA inspector verified the broken bolt on the scissor arm assembly. The bolt had failed on its threaded portion inside the castellated nut. The fracture surface was cleaned and examined under magnification. The examination revealed fracture features similar to fatigue cracking signatures with multiple ratchet marks emanating from the threads of the bolt. Maintenance records indicated that the helicopter had accumulated 4,196 flight hours prior to the accident, and the helicopter underwent an inspection on May 8, 1995, about 328 flight hours prior to the accident. ## Aircraft - Registration: [N38115](https://openairdocs.org/deregistered/N38115-2013-04-18), registration cancelled 2013-04-18, S/N 77-011, built 1977 (OpenAirDocs) - Reported make and model: TEXAS HELICOPTER OH-13E - Registry model: [Texas Helicopter OH-13H/M74A](https://openairdocs.org/model/texas-helicopter-oh-13h-m74a) (registry code 8930105) (OpenAirDocs) - Registry engine: [Lycoming VO-435 series](https://openairdocs.org/engine/lycoming-vo-435-series) (registry code 41525, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: 77-011 - Airframe hours: 4196 - Engines: LYCOMING VO-435-A1F 250 horsepower reciprocating - Damage: Substantial damage - Flight: Aerial application, Part 137 - Registered owner: Heli Flight Ag Service, Inc. - Airworthiness certificate: Special, Restricted (Special) - Last inspection: 100 hour, May 8, 1995, 328 hours before ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 37; commercial; airplane ratings: single-engine land; instrument ratings: helicopter, airplane; medical: class 2, valid medical--no waivers/lim.; seat: center; flight hours: 7,572 total, 2,657 in this make and model, 7,374 as pilot in command, 422 in the last 90 days, 100 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: 20° at 8 knots - Visibility: 60 statute miles - Lowest ceiling: none - Temperature: 73 °F, dew point 43 °F - Altimeter: 30.00 inHg - Observed at: YKM, 5 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 19950920046919A](https://openairdocs.org/incident/19950920046919A), Sep 20, 1995: Bell OH13H, Yakima, WA, Substantial damage. During spray ops. Collective went full pitch. Helicopter hopping. Ditched in pond. Scissor arm assembly bolt broke. 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.