Accident Details
On January 1, 2014, at approximately 1507 Pacific standard time, a Eurocopter EC-130 B4, registration N133GC, experienced a hard landing during an autorotation while on short final at Boulder City Municipal Airport (BVU) in Boulder City, Nevada. The helicopter, registered to Zuni LLC and operated by Papillon Airways, Inc. (PAI), was conducting a post-maintenance operational check flight under 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and a company flight plan was filed for the local flight, which departed at about 1457. The commercial pilot, the sole occupant, was not injured. The helicopter came to rest on its right side and sustained substantial damage to the fuselage and tail boom.
Pilot Report
According to a written statement, the pilot reported that she completed the post-maintenance operational check flight and was on short final to BVU at an altitude of about 200 feet above the ground and an airspeed of 40 to 50 knots. Shortly thereafter, the fuel pressure indicator light illuminated and the engine flamed out. The pilot stated that she lowered the collective to initiate an autorotation, but did not have sufficient airspeed to complete it successfully. During the accident sequence, the helicopter's tailboom impacted the ground first, followed by a hard landing that caused the skids to separate and substantial damage to the fuselage.
Postaccident Examination
A postaccident examination by a Federal Aviation Administration (FAA) inspector revealed that safety wire had been removed from a B-nut fitting that connects the main fuel supply to the aft side of the engine firewall, which delivers fuel to the engine's Hydro Mechanical Unit. The B-nut fitting was found to be loose when rotated by hand. The removed safety wire remained attached to hardware near the engine firewall.
Maintenance and Procedures
Maintenance records indicated that replacement of the bi-directional suspension cross-bar assembly was due, and the accident flight was the first flight since that task was performed. According to the FAA, several maintenance technicians at PAI stated that the method chosen to gain access for the replacement was contrary to the manufacturer's maintenance manual. Instead of removing the main gearbox as recommended, they defueled and removed the fuel tank. The defueling process involved disconnecting the main fuel supply line that delivers fuel to the engine Hydro Mechanical Unit, attaching the line to a tank on the ground, and pumping out the fuel using the helicopter's fuel boost pump. This task was performed by a non-certificated technician. Several maintenance technicians were aware of the tasks performed, yet none reported having followed the manufacturer's maintenance manual. The maintenance records contained no entry regarding the removal or disconnection of the main fuel supply line. The manufacturer's maintenance manual (Section 63-31-00, 4-1) recommends accessing the bi-directional suspension cross-bar assembly by removing the main gearbox, not by removing the fuel tank.
Postaccident Actions
Following the accident, PAI implemented a 16-step independent control check to their Safety Control System, to be conducted only by experienced maintenance inspectors. This system was complemented by the addition of exclusively assigned Maintenance Ops Check Pilots who provide an additional level of oversight. An internal maintenance training system was created with heavy focus on FAA regulations (CFR 39, 43, 91) and included onsite manufacturer's training programs covering airframe and engine systems.