Aircraft Accident/Incident Report

Grand Isle S108, -- 70357
Thursday, September 18, 1997 7:45 CDT

NTSB Narrative Summary Released at Completion of Accident

The helicopter was in cruise flight over open ocean water at 130 knots and 800 feet MSL, when the pilot felt a "violent jerk or yaw" and heard a grinding sound coming from the rear of the aircraft. The pilot attempted to correct the yaw with the anti-torque pedals, but there was no response, and the aircraft continued to yaw to the right and the nose pitched down. The pilot reduced the throttle and initiated an autorotation. He stated that the helicopter made "almost" a 360-degree right turn before contact with the water at a level pitch attitude with "slight" forward speed. One of the 4 passengers recalled seeing an object fall and hit the water, "leaving a circular motion" on top of the water, just prior to the helicopter landing in the water. The helicopter remained afloat on its deployed skid mounted float system and was recovered on the day of the accident, with the exception of the aft section of the tail boom, including the tail rotor gearbox, vertical fin, and tail rotor hub and blade assembly, which was missing. The aft section of the tail boom was recovered approximately 3 months later. Detailed examination of the tail boom separation area revealed multiple fractures and tears between tail boom stations 148 and 162. Examination of the fractured area revealed no evidence of fatigue. There was evidence of 4 tail rotor blade strikes between tail boom stations 150.9 and 153.2. One of the tail rotor blades was fractured about 14 to 18 inches from the inboard end, with the outboard section missing. The metallic leading edge of the remaining inboard section of this blade was deformed and twisted toward the tail boom. The other tail rotor blade was relatively intact with an indentation near the leading edge on the side toward the tail boom located about 18 inches from the inboard end of the blade. White paint, similar to the paint on the tail boom was found smeared onto the tail rotor blade's black paint in the area of the indentation. Detailed examinations of the tail rotor hub and blade assembly, tail rotor mast, tail rotor controls, tail rotor drive system, and the 90-degree gearbox mounting system did not reveal the reason for the in-flight contact of the tail rotor blades with the tail boom.

NTSB Probable Cause Narrative

The tail rotor blade strike(s) that severed the aft portion of the tailboom, subsequently rendering the pilot with no tail rotor control while in cruise flight. A factor was the lack of suitable terrain for the forced autorotative landing.

Event Information

Type of Event Accident
Event Date 9/18/1997
Event Day of the Week Thursday
Time of Event 745
Event Time Zone Central Daylight Time
Event City Grand Isle S108
Event State GULF OF MEXICO
Event Country --
Zipcode of the event site 70357
Event Date Year 1997
Event Date Month 9
MidAir Collision Indicator No
On Ground Collision occurred ? No
Event Location Latitude --
Event Location Longitude --
Event Location Airport --
Event Location Nearest Airport ID --
Indicates whether the acc/inc occurred off or on an airport Off Airport/Airstrip
Distance from airport in statute miles --
Degrees magnetic from airport --
Airport Elevation --
Weather Briefing Completeness Not pertinent
Investigator's weather source Pilot
Time of the weather observation
Direction of event from weather observation facility (degrees) --
Weather Observation Facility ID --
Elevation of weather observation facility --
Distance of event from weather observation facility (units?) --
Time Zone of the weather observation --
Lighting Conditions Day
Lowest Ceiling Height 4000
Lowest Non-Ceiling Height 1000
Sky/Lowest/Cloud Conditions Scattered
Sky Condition for Lowest Ceiling Broken
Visibility Runway Visual Range (Feet) 0
Visibility Runway Visual Value (Statute Miles) 0
Visibility (Statute Miles) 6
Air Temperature at event time (in degrees celsius) 25
Dew Point at event time (in degress fahrenheit) --
Wind Direction (degrees magnetic) 70
Variable Wind Indicator Wind direction could be determined
Wind Speed (knots) 16
Wind Velocity Indicator --
Wind Gust Indicator Not Gusting
Wind Gust (knots) --
Altimeter Setting at event time (in. Hg) 29.97
Density Altitude (feet) --
Intensity of Precipitation Light
METAR weather report --
Event Highest Injury Minor
On Ground, Fatal Injuries 0
On Ground, Minor Injuries 0
On Ground, Serious Injuries 0
Injury Total Fatal --
Injury Total Minor 4
Injury Total None 1
Injury Total Serious --
Injury Total All 4
Investigating Agency NTSB
NTSB Docket Number (internal use) 11826
NTSB Notification Source --
NTSB Notification Date Sep 18 1997 12:00AM
NTSB Notification Time 1630
Fiche Number and/or location -used to find docket information DMS
Date of most recent change to record Jun 4 2002 9:52AM
User who most recently changed record NTSB\MONR
Basic weather conditions Instrument Meteorological Cond
FAA District Office --

Aircraft Involved

Aircraft #1

Aircraft Registration Number N467PH
NTSB Number FTW97FA352
Missing Aircraft Indicator N
Federal Aviation Reg. Part Part 135: Air Taxi & Commuter
Type of Flight Plan filed Company VFR
Flight plan Was Activated? Yes
Damage Substantial
Aircraft Fire None
Aircraft Explosion None
Aircraft Manufacturer's Full Name Bell
Aircraft Model 407
Aircraft Series Identifier 407
Aircraft Serial Number 53142
Certified Max Gross Weight 5000
Aircraft Category Helicopter
Aircraft Registration Class U.S. Registered/U.S. Soil
Aircraft is a homebuilt? No
Flight Crew Seats --
Cabin Crew Seats --
Passenger Seats --
Total number of seats on the aircraft 7
Number of Engines 1
Fixed gear or retractable gear Fixed
Aircraft, Type of Last Inspection AAIP
Date of Last Inspection Sep 6 1997 12:00AM
Airframe hours since last inspection 35
Airframe Hours 177
ELT Installed Yes
ELT Activated No
ELT Aided Location of Event Site No
ELT Type --
Aircraft Owner Name G.E. Capital Corporation
Aircraft Owner Street Address 5400 LBJ Freeway
Aircraft Owner City Dallas
Aircraft Owner State TX
Aircraft Owner Country USA
Aircraft Owner Zipcode 75240
Operator is an individual? No
Operator Name PETROLEUM HELICOPTERS, INC.
Operator Same as Owner? No
Operator Is Doing Business As --
Operator Address Same as Owner? No
Operator Street Address 113 BORMAN DRIVE
Operator City LAFAYETTE
Operator State LA
Operator Country USA
Operator Zip code 70508
Operator Code HEEA
Owner has at least one certificate --
Other Operator of large aircraft? --
Certified for Part 133 or 137 Operation --
Operator Certificate Number --
Indicates whether an air carrier operation was scheduled or not Non-scheduled
Indicates Domestic or International Flight Domestic
Operator carrying Pax/Cargo/Mail Passenger Only
Type of Flying (Per_Bus / Primary) Unknown
Second Pilot on Board No
Departure Point Same as Event No
Departure Airport Code NONE
Departure City EWING BANKS-286
Departure State GM
Departure Country USA
Departure Time 729
Departure Time Zone CDT
Destination Same as Local Flt --
Destination Airport Code 7R1
Destination City VENICE
Destination State LA
Destination Country USA
Specific Phase of Flight Cruise
Report sent to ICAO? --
Evacuation occurred Yes
Date of most recent change to record May 14 2002 6:32PM
User who most recently changed record SNYG
Since inspection or accident Time of Accident
Event Location Runway Number and Location --
Runway Length --
Runway Width --
Sight Seeing flight No
Air Medical Flight No
Medical Flight --