# NTSB SEA99FA037: Hiller UH-12E, N2239, Yellow Pine, ID, February 28, 1999 - Type: NTSB accident investigation - Classification: Accident · No injuries · Field investigation · Final report - Date: February 28, 1999, 15:00 local (22:00 UTC) - Place: Yellow Pine, ID - Coordinates: 45.019893, -115.520523 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=45.0199&lon=-115.5205&mi=10 - Phase of flight: [Taxi](https://openairdocs.org/ntsb-phases/250) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 3 uninjured - Status: Completed, report June 23, 2000 - Report: Approved by Office Director - NTSB case key (mKey): 47409 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA99FA037 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/47409/pdf - Page: https://openairdocs.org/ntsb/SEA99FA037 ## Probable cause Altitude deviation during aerial taxi for undetermined reasons. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Altitude deviation,uncontrolled, taxi - aerial - reason for occurrence undetermined - Hard landing, descent - uncontrolled ## Analysis The aircraft departed the airport for the second surveillance flight of the day. Shortly after departure, the pilot was contacted by a ground crew member and informed that a 55 gallon fuel barrel was knocked over during the helicopter's departure. The pilot elected to returned to the airport and inspect the helicopter for possible damage that may have occurred. The pilot made a normal approach to the airport and was established in a hover taxi, when the helicopter suddenly began to descend. The pilot stated that he increased up collective without a response. The pilot then pulled full up-collective, however the helicopter continued to descend. The helicopter impacted terrain in a slightly nose-low attitude. After contacting the ground, the pilot released the collective and the main rotor blades struck and severed the tail boom assembly. The helicopter canted to the left and partially rolled to one side. At the time of the accident, the helicopter was operating near gross weight at an elevation of 3,835 feet mean sea level (MSL). ## Factual narrative On February 28, 1999, about 1330 mountain standard time, a Hiller UH-12E, N2239, registered to and operated by Valley Helicopter Service, was substantially damaged after it collided with terrain while landing at Taylor Ranch airstrip, located 28 nautical miles northeast of Yellow Pine, Idaho. A company visual meteorological conditions flight plan was filed for the 14CFR135 aerial observation flight. The commercial pilot and his two passengers were uninjured. The flight originated from Taylor Ranch approximately ten minutes prior to the accident. The operator was contracted by the State of Idaho Department of Fish and Game, to survey for elk in the Frank Church Wilderness Area. Prior to the accident, the operator had completed 50 hours of the 70 hour survey contract. The pilot, accompanied by two observers, departed the airport for the second surveillance flight of the day. Shortly after departure, the pilot was contacted by a ground crew member and informed that during the helicopter's departure, a 55 gallon fuel barrel was knocked over. It is not known if the helicopter made contact with the barrel or if it was blown over by the helicopter's rotor wash. The pilot elected to return to the airport and inspect the helicopter for possible damage that may have occurred. The pilot made a normal approach to the airport and was established in a hover taxi, about 20 feet above ground level (AGL), when the helicopter suddenly began to descend. The pilot stated that he increased up collective without a response. The pilot stated that he then pulled full up-collective, however the helicopter continued to descend and impacted terrain in a slightly nose-low attitude. The pilot stated the descent was similar to settling with power. After contacting the ground, the pilot released the collective and the main rotor blades struck and severed the tail boom assembly. The helicopter canted to the left and partially rolled to one side. At the time of the accident, the helicopter was operating near gross weight at an elevation of 3,835 feet mean sea level (MSL). The pilot stated the engine was producing rated power and there were no indications of a powerplant failure. The weather at the accident site, as reported by the pilot, was temperature 50 degrees Fahrenheit, winds calm, and a visibility of 15 miles. The aircraft wreckage was retrieved by personnel from Specialty Aircraft Services, Redmond, Oregon, and secured at their facility. The wreckage was inspected by National Transportation Safety Board investigators after it was moved to storage. The main cabin area was intact, but sustained substantial impact damage. The left skid was partially collapsed. The tail boom was severed and leading edge damage was noted to the main rotor blades. Control continuity was established from the cyclic to the cyclic pylon assembly and from the collective to the control rotor assembly. Four bolts that secure the ballast plate to the rotor assembly were found fractured. The assembly was removed and shipped to the National Transportation Safety Board materials lab for inspection. A Senior Metallurgist form the lab reported that the all four bolts displayed features that are consistent with overstress separation. At the completion of the inspection, the rotor head and ballast assembly were released to Specialty Aircraft. ## Aircraft - Registration: [N2239](https://openairdocs.org/deregistered/N2239-2022-12-31), registration cancelled 2022-12-31, S/N 2233, built 1963 (OpenAirDocs) - Reported make and model: Hiller UH-12E - Registry model: [Hiller UH-12E](https://openairdocs.org/model/hiller-uh-12e) (registry code 4360122) (OpenAirDocs) - Registry engine: [Allison 250-C20 series](https://openairdocs.org/engine/allison-250-c20-series) (registry code 03020, turbo-prop) (OpenAirDocs) - Category: Helicopter - Serial number: 2233 - Airframe hours: 7984 - Engines: Allison CAE 822690 320 horsepower turbo shaft - Damage: Substantial damage - Fire: Unknown - Flight: Aerial observation, Part 91 - Registered owner: Jim Pope - Airworthiness certificate: Standard, Normal - Last inspection: Annual, February 26, 1999, 51 hours before - Flight plan: Company VFR - Airport: Taylor Ranch ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 63; commercial; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 2, valid medical--w/ waivers/lim; seat: front; flight hours: 32,000 total, 31,074 as pilot in command, 250 in the last 90 days, 7 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Visibility: 15 statute miles - Lowest ceiling: none - Temperature: 50 °F ## 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 19990228001909A](https://openairdocs.org/incident/19990228001909A), Feb 28, 1999: Hiller UH12E, Taylor Ranch, ID, Substantial damage. Idaho fish and game 1963 Hiller UH-12E public use helicopter returned to land shortly after take-off for unknown reasons, and the tail rotor struck the ground… 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.