WPR10FA085

An uncommanded engine shutdown due to an improperly calibrated fuel control unit (FCU) and power turbine governor (PTG). Also causal was the operator’s inadequate maintenance practices and procedures that failed to properly assess and correct the FCU and PTG irregularities/deficiencies. Contributing to the accident was the Federal Aviation Administration inspector’s selection of an area for the simulated engine failure that offered limited choices for a full-touchdown autorotation.

As part of the required normal 6-month competency check for the commercial pilot, a Federal Aviation Administration (FAA) inspector was performing an examination of the pilot's competency in responding to a total loss of engine power event while in cruise flight. To perform this examination, the FAA inspector announced the beginning of the simulated power loss procedure and moved the fuel flow control lever out of the flight detent (the full forward, full open position) and back just enough to keep the lever from springing back into the detent; this was done to ensure that the engine was not supplying power to the rotor system during the autorotation. However, when the fuel flow control lever was moved, the helicopter yawed right and the generator out warning light illuminated, indicating that the engine had flamed out. The pilot briefly attempted a restart, but the engine exceeded the temperature limit and he discontinued the start attempt. Because of their close proximity to the ground, there was inadequate time to attempt another restart of the engine. The pilot-in-command (PIC) identified and proceeded toward a forced landing site. Due to obstructing trees in the touchdown zone below the area where the simulated engine out was conducted, the PIC overflew the trees with up collective input, leading to a decay of the main rotor rpm. Thereafter, insufficient rotor rpm remained to cushion the touchdown. Also, because of down-sloping terrain, the distance between the helicopter and ground level increased seconds before landing, thereby increasing the helicopter's absolute altitude and contributing to a hard impact with the ground. The fuel control unit and the power turbine governor were removed from the engine and taken to a test facility where they were installed on calibrated test benches and tested in accordance with the manufacturer’s test procedures. The results of the fuel control unit test showed that the internal parts all worked properly; however, the fuel flow at every test point was below the specified minimum limit. The results of the power turbine governor test revealed that the unit was out of specified limits at each test point. The discrepancies noted would affect the fuel flow at the high end of the schedule and is indicative of an improper rigging procedure. Examination of the unit showed that the maximum stop setting had been adjusted in the field and that the travel was set at 80 degrees instead of the required 86 degrees. While some of the discrepancies found during the tests of the fuel control unit and the power turbine governor are not serious, those at the low end of the fuel schedule are of particular concern. The minimum fuel flow, idle, and the cut-off settings were found to be below the manufacturer’s specified minimum limits; when combined with hysteresis, or the lagging of a physical effect on a body behind its cause, the chances of insufficient fuel flow being delivered to the engine during any engine deceleration maneuver (i.e., moving the throttle out of the flight detent) increases dramatically. When the FAA inspector moved the fuel flow control lever as the pilot was manipulating the collective during the beginning of the autorotation, it is likely that the unloading of the engine sent a signal to the fuel control unit to rapidly decrease the fuel flow at the same time the fuel control lever was being brought out of the flight detent and moved aft, which helped induce the flameout. Review of the operator’s flight and maintenance records found a pilot write-up that noted that about 9 months prior to the accident the engine had flamed out when the throttle was manipulated during the start sequence. The operator’s maintenance department was unable to find a reason for the event and released the helicopter back to service. The company pilots were aware that this particular helicopter had a “touchy throttle.” The pilot noted that, when operating the throttle lever in this particular helicopter, “you have to be gentle and slow with it as you retard the lever…if you pull it back to far or fast, it will shut off the fuel.” At least four prior instances of flameouts as a result of minor throttle movements were uncovered in deposition testimony of company pilots. All occurred on the ground and three of the flameouts happened as pilots were bringing the fuel flow control lever back toward ground idle during the post-flight engine cool down period. These instances were not documented in the maintenance records, and no records of attempted remediation were found.

HISTORY OF FLIGHT On December 16, 2009, about 1329, Hawaiian standard time, an Aerospatiale AS350BA(FX2), N87EW, operated by Sunshine Helicopters, Inc., Kahului, Maui, Hawaii, experienced a total loss of engine power during a simulated forced landing on the island of Maui about 1.3 miles southeast of the Hana (uncontrolled) airport. The helicopter impacted hard on uneven, downsloping, terrain and was substantially damaged. The commercial certificated pilot-in-command and the FAA inspector check pilot, who held an airline transport pilot certificate, were seriously injured. Visual meteorological conditions prevailed, and a company flight plan was filed. The instructional flight was performed under the provisions of 14 Code of Federal Regulations Part 91, and it originated from the Kahului Airport about 1257. The check pilot was the operator's assigned Federal Aviation Administration (FAA) principal operations inspector (POI). The purpose of the flight was for the POI to administer a 14 CFR Part 135.293 competency check ride to the pilot. Satisfactory completion of the check ride, and other requirements, would enable the pilot to continue operating Part 135 commercial air tours for his employer, Sunshine Helicopters, holder of an air carrier operating certificate. According to Sunshine's director of operations (DO), at the time of the flight the accident pilot was current in the operation of the helicopter. Several hours prior to the accident flight, the pilot had flown an air taxi flight in N87EW, and no maintenance squawks were noted. The helicopter operated normally, and it was dispatched for the pilot's use later in the day for his FAA check ride. The FAA coordinator reported to the National Transportation Safety Board investigator that performance of a simulated loss of engine power during this type of check ride was an authorized routine procedure used in evaluating the competency of airmen. The pilot and the FAA inspector were interviewed and provided written statements. The FAA inspector said that after he and the pilot completed the oral portion of the examination they then discussed what would be done on the flight. The check ride was to be a combined 14 CFR 135.299 and 135.293 check rides and a site air tour route review. The selection to fly to Hana reflected the need to integrate the tour check with the 135.299 and 135.293 check rides. During the briefing it was observed that there were Kona winds, fairly light but different from the usual northeast trade winds. A briefing was then conducted talking about the specific maneuvers to be performed during the check ride: 1) confined area pinnacle approaches, 2) site specific operations, 3) simulated engine power loss with a autorotation forced landing to 100 feet above ground level (agl) with a power recovery before touchdown, and 4) settling with power. The maneuvers would be done either going to or coming from Hana. The inspector said the helicopter flew fine throughout the entire flight. The inspector noted that they were about 3,000 feet mean sea level (msl) about 1 mile south of the Hana airport when he said "simulated forced landing" to the pilot. He said there is no defined flight idle position to put in the Fuel Flow Control Lever (which is basically the throttle; hereinafter referred to as the FCL) in to ascertain the power setting. He brought the throttle out of the full open flight run position detent and just aft enough back toward flight idle to keep it from springing back into the gate. The purpose of moving it out of the gate was to be certain the engine is not supplying power during the maneuver. He said that he and the pilot had briefed this prior to the flight and that they were to recover with power before getting too low. The pilot responded to the simulated loss of power by putting the collective down and he turned toward the Hana airport. The inspector questioned the pilot if he thought they were going to make it to the Hana airport. At that point he believed that the engine was no longer operating and he moved the FCL all the way forward back into the flight detent, but it appeared they were not going to get the engine back. The pilot did try to restart, but it was quickly evident that a restart was not an option due to the rapidly approaching ground. He said they were both looking for a suitable field, but there were not a lot to choose from. The only suitable area was the field the accident occurred in. He said the pilot did a good job trying to get to the field. The inspector said he remembers making a call to check the airspeed during the descent. . The pilot said it was a clear, VFR day with clouds at 2,500 to 3,000 feet. There were some scattered clouds in the area. The wind was light and variable in direction. The visibility was 5 to 10 miles. There is no weather reporting station at Hana. He said the flight began and they cruised about 1,500 feet along the shore line and went into the Hana Manu to Kano Falls, where he did site specific training and standoffs, then a confined area landing. He initiated the takeoff and they headed toward the coast line. Then, not long after that, the FAA Inspector initiated the simulated engine failure. The pilot said he became aware that the simulated forced landing had turned into a real forced landing when the helicopter yawed and then he saw the generator warning light illuminate. He said he and the FAA inspector talked briefly about making it to the Hana airport once they realized the engine had stopped running, but then he realized they did not have enough altitude. He entered a normal autorotation and chose a landing spot to his right. He looked at the throttle and initiated a relight by pushing the (FCL lever) throttle forward and the T4 temperature gauge went to 855 degrees. Since that was over limits, he backed the FCL off to 700 degrees and then due to their altitude, was more focused on getting to the landing spot. He aborted the restart because the helicopter was getting low, about 1000 feet agl. There were not a lot of spots to choose from. There was a lot of grass and trees in the area. Since trees can penetrate the helicopter structure, he picked the grass area that they ultimately impacted. During the final part of the descent, about 150 feet agl, there was a low rotor rpm horn just before touchdown. The pilot said he did not see the FAA inspector reach over to the throttle quadrant, nor did he see him retard the FCL to begin the simulation. The FAA inspector said something like, "simulated engine failure is beginning". He said he was not surprised when the simulation began, and that he was expecting a simulated engine failure maneuver to be performed during the check ride. During this check ride, this was the first simulated engine failure that the FAA inspector had given him. He said that prior to the maneuver the FAA inspector was trying not to distract him and was very straight forward and was very open for questions. The pilot described movement of the FCL lever (throttle) in this particular helicopter as “you have to be gentle and slow with it as you retard the lever. If you pull it back to far or fast, it will shut off the fuel.” PERSONNEL INFORMATION Pilot-in-Command, Sunshine Helicopter The pilot, age 42, holds a commercial pilot certificate with a rotorcraft-helicopter and helicopter instrument ratings, the most recent issuance of which is dated June 8, 2004. In addition he held a flight instructor certificate with a rotorcraft helicopter rating that was issued on September 10, 2004. His most recent medical certificate, a second class, was issued on March 21, 2009, without limitations or waivers. According to the operators records, the pilot had accrued a total flight time of 4,458 hours, all in rotorcraft, with 662 in the AS350BA(FX). His most recent 14 CFR 135.293 and 135.299 checks were accomplished o