# NTSB LAX02TA267: Sikorsky S-55T, N747A, Lytle Creek, CA, August 30, 2002 - Type: NTSB accident investigation - Classification: Accident · No injuries · Final report - Date: August 30, 2002, 10:06 local (17:06 UTC) - Place: Lytle Creek, CA - Coordinates: 34.235, -117.496948 - Nearby events: https://openairdocs.org/map.md?lat=34.2350&lon=-117.4969&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report February 5, 2004 - Report: Approved by Office Director - Parties: Federal Aviation Administration - NTSB case key (mKey): 55603 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX02TA267 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/55603/pdf - Page: https://openairdocs.org/ntsb/LAX02TA267 ## Probable cause Failure of the hydraulic system due to contamination in the hydraulic fluid, which resulted in an in-flight loss of control. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, cruise - hydraulic system - contamination,water (cause) - hydraulic system - contamination,other than water (cause) - hydraulic system - failure (cause) - Loss of control - in flight, emergency descent/landing - rotorcraft flight controls - not available, pilot in command (cause) - In flight collision with terrain/water, emergency descent/landing - terrain condition - ground ## Analysis The helicopter collided with terrain while attempting a precautionary landing due to a hydraulics system failure. The helicopter was engaged in firefighting water drops. While returning to pickup additional fuel, and make bucket repairs, the red hydraulic failure light illuminated and the flight controls became stiff. About 10 feet above the ground, the cyclic flight control moved "hard over," which resulted in the nose moving up and to the right until the main rotor blades contacted the ground. The helicopter came to rest on its right side. Post crash examination by a laboratory revealed contamination of the hydraulic fluid by water and microbial growth. ## Factual narrative On August 30, 2002, at 1006 Pacific daylight time, a Sikorsky S-55T, N747A, collided with terrain while attempting a precautionary landing in a dry creek bed in Lytle Creek, California. The helicopter sustained substantial damage and the commercial pilot, the sole occupant, was not injured. The U.S. Forest Service was operating the helicopter as a fire suppression unit under the provisions of 14 CFR Part 133. The flight originated from a temporary helipad about 0830. Visual meteorological conditions prevailed and no flight plan had been filed. The Forest Service reported that the helicopter had been engaged in water bucket support on a fire for about 2 hours. During the last water drop the bucket failed to release the water. Repeated attempts to release the water failed so the pilot decided to return to base and refuel and repair the bucket. The pilot stated that a red hydraulic warning light illuminated and the flight controls became stiff. He began a precautionary approach to an open area. About 10 feet above the ground, the cyclic flight control moved "hard over," which resulted in the nose moving up and to the right. The pilot was unable to regain control before the main rotor blades made contact with a rocky shelf. The helicopter came to rest on its right side. Post crash examination of the wreckage by the Forest Service investigation team did not reveal evidence of ruptured hydraulic lines. They took a sample of hydraulic fluid from the reservoir and stated that it appeared to be severely contaminated. Post crash examination by a laboratory revealed contamination of the hydraulic fluid by water and microbial growth. ## Aircraft - Registration: [N747A](https://openairdocs.org/deregistered/N747A-2004-01-16), registration cancelled 2004-01-16, S/N 55910, built 1956 (OpenAirDocs) - Reported make and model: Sikorsky S-55T - Registry model: [Sikorsky S-55](https://openairdocs.org/model/sikorsky-s-55) (registry code 8141602) (OpenAirDocs) - Registry engine: [AiResearch TPE331 series](https://openairdocs.org/engine/airesearch-tpe331-series) (registry code 01517, turbo-prop) (OpenAirDocs) - Category: Helicopter - Serial number: 55-910 - Airframe hours: 12689 - Engines: Garrett-AiResearch TSE 331-3LL 800 horsepower turbo shaft - Damage: Substantial damage - Flight: Public aircraft, Part 133 - Registered owner: Central Sierra Helicopters - Airworthiness certificate: Standard, Normal - Last inspection: Annual, October 20, 2001, 74.7 hours before - Departed: LYTLE CREEK, CA ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 32; injuries: none; commercial, flight instructor; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 2, valid medical--w/ waivers/lim; last flight review July 11, 2002; seat: right; flight hours: 1,815 total, 85 in this make and model, 1,719 as pilot in command ## Weather - Conditions: Visual (VMC), Day - Wind: 190° at 3 knots - Visibility: 7 statute miles - Lowest ceiling: none - Temperature: 84 °F, dew point 48 °F - Altimeter: 29.90 inHg - Observed at: KONT, 15 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 20020830022079A](https://openairdocs.org/incident/20020830022079A), Aug 30, 2002: Skrsky S55, Lytle Creek, CA, Substantial damage. (.19) On August 30, 2002, at 1006 hours pacific daylight time, a Sikorsky S-55T, N747A, collided with terrain while attempting a precautionary landing in a dry… ## Other investigations on N747A (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 ANC67A0021](https://openairdocs.org/ntsb/ANC67A0021), Aug 20, 1966: Sikorsky S-55 (N747A), Galena, AK, substantial damage 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.