# NTSB FTW01LA121: Eurocopter AS-350-B2, N311TV, Houston, TX, May 18, 2001 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: May 18, 2001, 09:25 local (14:25 UTC) - Place: Houston, TX - Coordinates: 29.610975, -95.120208 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=29.6110&lon=-95.1202&mi=10 - Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed, report September 27, 2001 - Report: Approved by Office Director - Parties: Federal Aviation Administration - NTSB case key (mKey): 52285 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW01LA121 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/52285/pdf - Page: https://openairdocs.org/ntsb/FTW01LA121 ## Probable cause the failure of the pilot to maintain control of the helicopter following an inadvertent deactivation of the hydraulic system, during final approach. A contributory factor was the unguarded hydraulic cut-off switch. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of control - in flight, approach - vfr pattern - final approach - electrical system,electric switch - not secured - hydraulic system - inadvertent deactivation, pilot in command (cause) - aircraft control - not maintained, pilot in command (cause) - In flight collision with terrain/water, descent - uncontrolled - airport facilities,helipad ## Analysis The helicopter was on final approach, approximately 15 feet above the roof top helipad, when the helicopter's controls "became very stiff." The pilot observed the "HYD" light on the caution panel illuminated; however, the audible hydraulic warning horn did not activate. Subsequently, the helicopter impacted the helipad with the right skid, and rolled onto its right side. Examination of the helicopter's cockpit revealed that the hydraulic cut-off switch, which is located on the collective control, was found in the cut-off position and its red plastic guard was broken (when the switch is in the cut-off position the hydraulic warning horn will not sound). The cockpit was examined for shattered pieces of the guard; however, none were found. The hydraulic system was examined and no leaks were noted. A functional test of the hydraulic pump and regulator/manifold revealed no anomalies with either unit. ## Factual narrative On May 18, 2001, at 0925 central daylight time, a Eurocopter AS-350-B2 helicopter, N311TV, was substantially damaged while landing when it impacted the helipad at the KHOU-TV heliport near Houston, Texas. The helicopter was registered to and operated by U.S. Helicopters Inc., of Marshville, North Carolina. The commercial pilot, sole occupant of the helicopter, sustained minor injuries. Visual meteorological conditions prevailed and a company visual flight rules (VFR) flight plan was filed for the 14 Code of Federal Regulations Part 91 business flight. The local flight originated from the Sugarland Municipal Airport, Houston, Texas, at 0915, and was destined for the KHOU helipad. According to the pilot, during the approach to the roof top helipad, just as the helicopter crossed over the edge of the building (approximately 15-20 feet above the helipad), the helicopter's controls "became very stiff." He looked at the caution panel and noted that the "HYD" light was illuminated; however, the hydraulic warning horn did not activate. Subsequently, the helicopter impacted the helipad with the right skid, and rolled over onto its right side. Two FAA inspectors and a representative from American Eurocopter examined the helicopter and the accident site. They reported that the hydraulic cut-off switch, which is located on the collective control, was found in the cut-off position (when the switch is in the cut-off position the hydraulic warning horn will not sound). The switch's red plastic guard was found broken, therefore exposing the switch. The cockpit was examined for shattered pieces of the guard and no pieces were recovered. The emergency responders did not indicate that they had moved the hydraulic cut-off switch. The main rotor servos, the hydraulic pump and hydraulic lines were examined, and no leakage was noted. The hydraulic pump pulley/belt assembly was intact. The belt was examined for thermal damage and slippage marks, and none were observed. The hydraulic pump and regulator/manifold were removed from the helicopter for a functional test. All three main rotor blades were damaged and the engine mounts and the tail rotor drive shaft were separated. The hydraulic pump and regulator/manifold were functionally tested at American Eurocopter, Grand Prairie, Texas, under supervision of the NTSB. The pump operated within manufacturer's specifications and no anomalies were noted. According to a report provided by American Eurocopter, "the pump provided continuous hydraulic pressure once primed, and the manifold/regulator kept the pressure constant at 40 bars while supplied by the pump." The helicopter's maintenance logbooks and records were reviewed. On April 21, 2001, the airframe and engine underwent their most recent 100-hour inspections at which time the airframe and engine had accumulated a total of 1,751.3 hours. No additional pertinent logbook entries were noted. ## Aircraft - Registration: [N311TV](https://openairdocs.org/deregistered/N311TV-2001-12-13), registration cancelled 2001-12-13, S/N 3024 (OpenAirDocs) - Reported make and model: Eurocopter AS-350-B2 - Registry model: [Eurocopter AS 350 B2](https://openairdocs.org/model/eurocopter-as-350-b2) (registry code 8680950) (OpenAirDocs) - Category: Helicopter - Serial number: 3024 - Airframe hours: 1790.7 - Engines: Turbomeca Arriel 1D1 732 horsepower turbo shaft - Damage: Substantial damage - Flight: Business, Part 91 - Registered owner: U.S. Helicopters Inc. - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, April 21, 2001, 39.4 hours before - Departed: SGR, Houston, TX - Destination: 66TS, Houston, TX - Flight plan: Company VFR - Airport: 66TS, KHOU-TV Heliport, runway H1, 50 × 50 ft, concrete ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 52; injuries: minor; flight instructor, commercial; instrument ratings: helicopter; medical: class 2, valid medical--no waivers/lim.; last flight review September 13, 2000; seat: right; flight hours: 11,250 total, 5,470 in this make and model, 10,400 as pilot in command, 175 in the last 90 days, 50 in the last 30 days, 3 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 190° at 11 knots - Visibility: 10 statute miles - Lowest ceiling: 2,300 ft broken - Temperature: 81 °F, dew point 70 °F - Altimeter: 29.94 inHg - Observed at: HOU, 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 20010518020349A](https://openairdocs.org/incident/20010518020349A), May 18, 2001: Houston, TX, Substantial damage. (.19) On may 18, 2001, at 0940 central daylight time, a Eurocopter AS-350-B2 helicopter, N311TV, was substantially damaged during an approach when it impacted… 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.