Recent Update Of NTSB Investigation Seems To Suggest That Possibilty

In its continuing investigation of the January 4, 2009, fatal accident involving a Sikorsky S-76C++ helicopter, operated by PHI, Inc., that crashed in a marsh near Morgan City, Louisiana (NTSB Accident Number CEN09MA117), the National Transportation Safety Board is releasing the following factual information:

During the first of two detailed examinations of the wreckage layout last month in Lafayette, Louisiana, a bird specialist with the U.S. Department of Agriculture (USDA) examined the helicopter for evidence of a bird strike. A visual examination did not detect any such evidence, but a swab was taken from the pilot-side windscreen. The sample was sent to the Smithsonian Institution Feather Identification Lab for identification. Results from DNA testing on that sample showed that microscopic remains of a hawk variety were present. The swab was taken from an area of the windscreen that exhibited concentric ring fractures. Similar concentric rings were visible in the gel coat of the fuselage area just above the windscreen.

A second detailed examination of the wreckage layout was conducted this past week in Lafayette, with additional NTSB and USDA specialists. Additional swabs for bird remains were taken from the fuselage; empennage; various inlets, including the engines; and from the rotor hub and main rotor blades. Additionally, examination revealed the presence of small parts of feathers under a right side windscreen seal and in the folds of the right side engine inlet filter.

Portions of the windscreen and composite center post are continuing to be examined in the NTSB laboratory in Washington, DC for further structural analysis and a review of material specificity.

The original production laminated glass windscreens from the accident helicopter had been removed and replaced by PHI about two years prior to the accident as part of their normal procedures with the S-76 fleet in order to prepare for operational mission status. This helicopter's windscreens were replaced a second time due to cracking approximately one year prior to the accident. PHI replaces all of the windscreens in their S-76 fleet with a lighter weight, cast acrylic windscreen that was approved by the Federal Aviation Administration (FAA) via a Supplemental Type Certificate (STC) upon delivery.

The ongoing investigation will involve further analysis of the information from the cockpit voice and flight data recorders, detailed examination and analysis of the damage to the cast acrylic and composite center post, investigation into the windscreen STC issuance and specifications, research into the potential scenarios that could cause the loss of engine torque and electrical anomalies noted on the flight recorders, and the flight crew's response to the event.

FMI: www.ntsb.gov