Fatal Crash Causes the NTSB to Suggest Changes to Helicopter Design Maintenance

Photo of Daniel Horowitz

As noted by the New York Times and Associated Press, on November 24, 2010 the National Transportation Safety Board (NTSB) recommended a redesign and modification of some portions of the Sikorsky S-76C helicopter, as a result of a January 4, 2009 helicopter crash which resulted in numerous fatalities.

The NTSB sent 12 safety recommendations to the Federal Aviation Administration (FAA) as part of its formal report issued in regards to the January 4, 2009 dual-engine helicopter crash, operated by PHI, Inc. The Sikorsky helicopter was in transit from Amelie, Louisiana to an oil platform in the Gulf of Mexico. The helicopter was only in the air for about 7 minutes prior to the crash.

Federal investigators believe that a bird struck the helicopter at an altitude of 850 feet above ground. Investigators found the remains of a red-tailed hawk on the remnants of the pilot’s side windshield. There were also bird feathers found under a windscreen seal and in one of the engines of the helicopter. A cockpit voice recorder captured a loud bang and subsequent piercing air noise roughly 17 seconds before the crash. Also on the audio recorder, you can hear the pilot’s and co-pilot’s confusion as to why the windshield buckled.

According to the NTSB report, the helicopter was originally equipped with a laminated glass windshield that complied with European bird-strike resistance standards. PHI, Inc. then replaced those windshields with aftermarket cast acrylic windshields that did not meet any bird-strike resistance standard. In its report, the NTSB stated that the impact of the bird on the canopy just above the windshield “likely jarred the fire extinguisher T-handles out of their detents and moved them and moved them aft, pushing both engine control levers into or near the flight idle position, reducing fuel to both engines. The pilots were probably disoriented from the broken windshield and rushing air and were unable to react in time to maintain control of the helicopter.”

As part of the safety recommendations, the NTSB stated that the FAA should prohibit operators of helicopters with installed bird-strike resistant windshields from replacing those windshields with ones that have not been tested to withstand such strikes. Also, the NTSB suggested that the company redesign the model to ensure that fire extinguishers do not inadvertently dislodge due to any external force on the canopy or windshields. The NTSB further suggested evaluating other helicopter models with engine control quadrant designs similar to the Sikorsky S-76C model and requiring modifications as necessary.

Other recommendations include: evaluating the feasibility of retrofitting helicopters manufactured before 1996 and requiring manufacturers to equip new helicopters built under the old certification requirements with windshields that meet the current bird-strike requirements, requiring Sikorsky to design an audible alarm system and master warning light that will alert the flight crew when there are low rotor revolutions per minute, and requiring manufacturers to develop helicopter-specific guidance that will help pilots devise precautionary strategies for minimizing the severity of helicopter damage sustained during a bird-strike.