N407MM

HISTORY OF FLIGHT

On December 29, 2000, at approximately 0730 central standard time, a Bell 407 helicopter, N407MM, registered to The Fifth Third Leasing Co., of Cincinnati, Ohio, and operated by Petroleum Helicopters Incorporated (PHI), of Lafayette, Louisiana, was destroyed when it impacted offshore waters in an uncontrolled descent in the Gulf of Mexico, approximately 6 miles south of Gilchrist, Texas. The commercial pilot, who was the sole occupant, sustained fatal injuries. Visual meteorological conditions prevailed and a company flight plan was filed for the Title 14 Code of Federal Regulations Part 91 repositioning flight. The flight departed Cameron, Louisiana, at 0713, and was en route to Galveston, Texas, with an estimated time of arrival (ETA) of 0750 .

According to the operator's refueling logs, the aircraft was fueled to capacity (863 pounds) with Jet-A fuel prior to departing Cameron. The operator's daily communications log and audio tape revealed that the pilot made a routine position report at 0728 on the PHI en route frequency. The pilot reported that he was at 29 degrees, 38 minutes North latitude, and 93 degrees, 57 minutes West longitude. This was the last known contact with the helicopter. At 0751, repeated attempts to contact N407MM by the PHI Sabine Communications Center were made, but to no avail. At 0810, N407MM was reported overdue and the company search plan was activated. For the remainder of the day, search helicopters flew the presumed flight path of N407MM and the adjacent offshore areas with no sightings of the helicopter, pilot, or debris. There were no reported witnesses to the accident.

PERSONNEL INFORMATION

The pilot was hired by PHI on February 10, 2000, and held a commercial pilot certificate with rotorcraft-helicopter and instrument ratings. His total reported flight time, as of 29 December, 2000, was 1,984 hours, all of which were in light helicopters. His total flight time in the Bell 407 was 58 hours. He had flown 100 operational flight hours in single-engine helicopters in the 90 days prior to the accident.

AIRCRAFT INFORMATION

PHI purchased the helicopter, serial number (S/N) 53060, as a new aircraft in March 1996. It had a total airframe time of 4,429.35 hours at the time of the accident. The helicopter was equipped with an Allison 250C47B turbo shaft engine (S/N CAE847289), and it had a total time of 1,770 hours. According to maintenance records provided by the operator, the last 25-hour inspection was completed on December, 26, 2000 at 4,421.5 hours, and the last 50-hour inspection was completed on December 19, 2000 at 4,407 hours.

On December 24, 2000, at an aircraft total time of 4,418.4 hours, the tail rotor hub and blade assembly was removed due to worn bearings in the pitch change links and hub. A replacement tail rotor hub and blade assembly, S/N 53209, was installed. The hub and yoke components of this assembly had a total time of 37 hours at the time of installation and both blades (which were removed from the previous yoke assembly) had accumulated total times of 2,433.5 hours respectively. On December 28, 2000, at 4,429 hours aircraft total time, the tail rotor mast retaining nut torque check, required 10 to 25 hours after installation of the assembly as per the manufacturer’s maintenance manual, was performed. The entry in the logbook for the torque check stated that there was "no movement" of the retaining nut during the check, and the technician stated in an interview that there was no disassembly required to perform the torque check. A torque check was also done on the #1 and #2 tail rotor drive shaft disc couplings. This torque check was required as per the manufacturer's maintenance manual since the #1 and #2 drive shafts were removed and re-installed during the previous 100-hour inspection.

According to records provided by the FAA, the manufacturer, and the operator, N407MM was in compliance with all applicable airworthiness directives pertinent to the Bell model 407 helicopter. Additionally, all required modifications for the helicopter to operate at 140 knots Vne were verified to have been installed. These modifications included a newly designed tail rotor hub, and an airspeed activated tail rotor pedal stop.

COMMUNICATIONS

According to PHI operating procedures, the helicopter's transponder should have been turned on with a beacon code of 4345. A military radar source provided radar contact information about a target using code 4345 which was traveling at about 1,000 feet MSL. According to PHI, the target's path corresponded to the planned flight path of N407MM. The first radar contact was at 0725:51 at 29 degrees, 45'33" North latitude, and 93 degrees, 52'04" West longitude. The last radar contact was at 0726:15 at 29 degrees, 40'14" North latitude, and 93 degrees, 51'49" West longitude. No distress calls were monitored on offshore radio frequencies.

WRECKAGE AND IMPACT INFORMATION

The main aircraft wreckage was located in 32 feet of water on January 2, 2000, at grid coordinates 29:25 N longitude 94:32 W latitude, and transported to the PHI facility in Lafayette, Louisiana. These recovered portions included the main fuselage with part of the tail boom (forward section attached to the fuselage), the main rotor drive system and blades, the engine, and the landing gear and skid mounted float assembly. On January 6, 2001, another section of the tail boom (middle section) was recovered after being located floating in the Gulf of Mexico about 75 miles southwest of the main wreckage, and was transported to the PHI facility. On March 28, 2001, the aft portion of the tail boom with the vertical fin attached washed ashore near Sabine Pass, Texas, and was recovered. The tail rotor gearbox housing and gears, tail rotor mast, tail rotor hub and blade assembly, and the aft section of the tail rotor drive shaft were missing. As of the date of this report, these parts have not been recovered.

Various examinations of the recovered components were conducted under the supervision of the NTSB investigator-in-charge at the PHI facility, Lafayette, Louisiana, on January 3-10, 2001 and at the Bell materials lab, Hurst, Texas, from February 28 to March 16, 2001 and April 2-4, 2001. The following are summaries of these examinations.

Engine

The engine was removed from the wreckage and secured to a work stand for examination. The Electronic Control Unit (ECU) was found intact with harnesses connected. The unit exhibited only superficial scarring damage to the cover. During handling, it was determined that the unit contained water. Per consultations with a representative of Chandler Evans Controls (CECO) Division, it was decided to open the unit, drain and flush it with distilled water, and send it to CECO, West Hartford, Connecticut, for download of data. The ECU download did not record any faults or incidents.

The engine gearbox exhibited extensive corrosion damage attributed to salt water immersion. The left side of the engine exhibited extensive impact damage from the diffuser scroll aft to the outer combustion case, which had several indentations. Two impeller blades (about 180 degrees apart) were bent approximately 30-degrees, opposite direction of rotation and the liner exhibited heavy rotational scoring at the impeller blade rotational path. The Hydro-Mechanical Unit (HMU) was found intact and approximately 12 inches of the linkage was attached to the control quadrant. The control lever operated normally through its full range. All fluid, oil, fuel, and air lines were found attached and their fittings were hand tight. The airframe fuel filter was intact, clean, and fuel was present in the filter housing. Approximately 20 cc's of fuel was present in the fuel nozzle line. Both engine chip detectors, upper and lower, were clean of metallic particles.

Fuselage

Much of the airframe was still wet, and mud covered much of the main rotor head when initially examined. Most of the cabin structure (especially the left side) exhibited evidence of hydraulic compression along its longitudinal axis. The nose section was connected to the center fuselage section by tangled wires and the roof section was connected by the engine throttle cable and engine bleed air line, both of which were located in the vertical tunnel (broom closet). The center and right hand nose sections were twisted and broken apart and the nose section was broken away from the forward floor structure. The pilot's seat pan exhibited no downward deformation and the seat back, including the inertial reel was missing. The upper circuit breaker panel was indented and deformed upward and the deformed area had a piece of brownish black hair embedded within the indentation. The rear portion of the fuselage (transition area from the rear bulkhead to the tail boom) was separated from the forward fuselage generally along a vertical line just aft of the fuel bladder cavity. About a 33-inch section of the tail boom remained attached to the rear bulkhead. The roof structure that attached to the engine was missing and the top portion of the rear fuselage from the forward part of the oil cooler was intact rearward to the tail boom attach point. The baggage compartment door was missing.

Tail Boom

The tail boom was fractured/separated in two places along its longitudinal axis. The forward most fractures consisted of multiple vertical and horizontal fractures, starting at about 33 inches aft of the tail boom to fuselage attachment point and ending at about 56 inches aft of the attachment point. The fractures on each side of the separation did not match and some tail boom skin was missing between the fractures. Some deformed skin pieces on both sides of the separation were displaced to the right. One piece, that was curled, had what appeared to be white paint smeared onto its surface. The color of the white paint smear was similar to ...