Accident Sikorsky S-76A N90421, 06 Sep 2005
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ASN Wikibase Occurrence # 19039
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Type:Silhouette image of generic S76 model; specific model in this crash may look slightly different    
Sikorsky S-76A
Owner/operator:Houston Helicopters, Inc.
Registration: N90421
MSN: 760039
Fatalities:Fatalities: 0 / Occupants: 12
Other fatalities:0
Aircraft damage: Written off (damaged beyond repair)
Location:Gulf of Mexico -   United States of America
Phase: En route
Departure airport:Gom A346, TX
Destination airport:Sabine Pass, TX
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
About 18 minutes into the flight, the No. 1 (left) engine fire warning light illuminated in the cockpit, followed by several additional engine warnings and visible smoke in the cockpit and passenger compartment, according to crew and passenger interviews. After the fire and smoke indications, the helicopter lost power to both engines, and the flight crew executed a forced landing into the open waters of the Gulf of Mexico. The helicopter wreckage was located, and the cockpit voice recorder (CVR) was recovered shortly after the accident; however, efforts to recover the remainder of the wreckage were suspended due to an approaching hurricane. The wreckage could not be located following the hurricane; therefore, the cause of the in-flight fire warnings and the loss of power to both engines could not be determined.

After the first engine fire warning, CVR evidence revealed that, contrary to their training and the helicopter manufacturer's guidance, neither pilot acknowledged the fire warning, called for a checklist, or verbalized a plan of action. According to the Sikorsky S-76A Flight Manual, the emergency procedures for responding to an engine fire warning include pressing the fire warning light, establishing safe single-engine flight airspeed (76 knots), fully retarding the affected engine's illuminated T-handle (a handle located on the engine throttle quadrant above and in front of the pilots, which, when pulled, stops the flow of fuel to that engine and releases a fire suppressant), and, if necessary, selecting and activating the fire extinguishing system. The pilots, who had been on duty for more than 10 hours and had completed 13 landings that day, only completed the first step during the 2 minutes before impact with water; therefore, the pilots failed to follow emergency procedures in response to the engine fire warning. National Transportation Safety Board performance calculations indicated that, if the pilots had immediately completed the first three steps in responding to the No. 1 engine fire warning, as required, they may have been able to maintain single-engine flight to a suitable landing location on an off-shore platform before the No. 2 engine failed.

The investigation revealed additional flight crew performance deficiencies. For example, although the first officer transmitted a "mayday" call before the second engine failure and about 1.5 minutes after the first warning indication, he did not provide essential information needed to obtain emergency assistance. He also did not inform the passengers that they were executing a forced landing into the water. Before flight, the flight crew did not provide the required preflight passenger safety briefing, which would have included instructions on how to retrieve and inflate a liferaft; the passengers did not retrieve either of the two liferafts. All of these performance deficiencies are consistent with the known effects of situational stress (in this case associated with the emergency) and fatigue (associated with a long, demanding day of flying), both of which likely degraded the pilots' performance.

The flight crew did not file a flight plan with either the Federal Aviation Administration (FAA) or HHI, contrary to company procedures. Although Houston area air traffic control (ATC) facilities were monitoring emergency frequencies, controllers did not hear the distress call because the helicopter was well outside and below ATC radio coverage when the transmission was made. Commercial and military pilots in the area reported hearing the distress call to various ATC facilities; however, none of the reporting pilots could provide any additional information about the distressed aircraft because the first officer had only stated, "mayday ... Houston 421... going in" and did not provide a location or type of emergency.

Probable Cause: The pilots' delayed response to the No. 1 engine fire warning and the loss of power to both engines, which occurred for undetermined reasons. The pilots' delayed response was most likely due to stress and fatigue. Contributing to the delay of the initiation of search and rescue operations were the pilots' incomplete "mayday" call, the pilots' and Houston Helicopter, Inc.'s (HHI's) noncompliance with company and Federal Aviation Administration (FAA) flight-following requirements, and HHI's inadequate communications contingencies and procedures for reporting overdue flights. Also contributing to the delay of search and rescue operations was the FAA's inadequate surveillance of previously identified company deficiencies, including HHI's lack of adequate flight-following procedures. This lack of surveillance allowed HHI's corporate culture to remain lax with regard to safety.




Safety recommendations:

Safety recommendation A-07-87 issued 18 October 2007 by NTSB to FAA
Safety recommendation A-07-88 issued 18 October 2007 by NTSB to FAA
Safety recommendation A-09-1 issued 2 February 2009 by NTSB to FAA

Revision history:

17-May-2008 11:10 ASN archive Added
14-Jun-2010 10:21 TB Updated [Date, Time, Aircraft type, Registration, Cn, Operator, Total fatalities, Total occupants, Other fatalities, Location, Country, Phase, Nature, Departure airport, Destination airport, Source, Damage, Narrative]
21-Jun-2010 13:21 TB Updated [Departure airport, Destination airport, Narrative]
21-Dec-2016 19:14 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
21-Dec-2016 19:16 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
21-Dec-2016 19:20 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
06-Dec-2017 11:00 ASN Update Bot Updated [Aircraft type, Operator, Departure airport, Source, Narrative]
04-Nov-2018 12:49 harro Updated [Narrative]

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