NTSB Factual Report

On December 31, 2014, about 1330, Pacific standard time, an MD Helicopter Inc. 369FF, N530KK, was substantially damaged during an emergency autorotation landing following a sudden loss of engine power in Las Vegas, Nevada. The two commercial pilots on board sustained serious injuries. The helicopter was registered to, and operated by, the Las Vegas Metropolitan Police Department as a public aircraft flight. Visual meteorological conditions prevailed, and no flight plan was filed. The local flight originated from North Las Vegas Airport (VGT), Las Vegas, at 1322.

The pilot reported that he had taken off with 64 gallons of fuel and was orbiting over a fixed location when he noticed a drop in engine and rotor revolutions per minute (rpm). The pilot then rolled the helicopter out of the orbit, and the engine and rotor rpm stabilized momentarily at 97%. The pilot attempted to increase the engine and rotor rpm while turning west towards the North Las Vegas Airport. During the maneuver, the engine and rotor rpm rapidly degraded. The pilot entered an autorotation, and executed an emergency landing. The helicopter touched down hard, the tail impacted the ground, and separated from the airframe.

The helicopter was examined on-scene by a Federal Aviation Administration (FAA) inspector. The inspector stated that he was only able to look at one side of the engine because of how the helicopter was positioned on the ground, and that he did not identify anything unusual. He checked the flight controls and reported that everything was connected. The helicopter was recovered to the Las Vegas Metro Police Department's hangar at the North Las Vegas Airport. Two FAA inspectors examined the helicopter on January 7, 2015, and reported that the engine outer combustion chamber, external fuel line connected to the fuel nozzle, and the fuel nozzle connection had sustained impact damage. Additionally, the engine fuel nozzle b-nut was "finger tight."

On January 14, 2015, representatives from MD Helicopters and Rolls-Royce examined the helicopter with oversight provided by a FAA inspector. The helicopter sustained substantial damage to the lower fuselage structure, aft fuselage section, tailboom and landing gear. There was no damage to the main structural members of the fuselage and the transmission/static mast support structure. The aft cabin was intact with no visible damage. The underside of the fuselage displayed damage to the belly skin and supporting interior structure with major damage to the aft landing gear fitting and center beam.

The top aft surface of the composite engine air fairing showed evidence of main rotor blade contact along with the tailboom. The tailboom was severed into two segments. The forward segment was still attached to the upper aft boom fairing. The vertical and horizontal stabilizer were both firmly attached to the aft segment. The vertical stabilizer's stinger was broken off and the vertical and horizontal stabilizers both displayed impact damage from ground contact. The aft portion of the left and right landing gear struts were broken and splayed outward resulting in the helicopter coming to rest on the lower fuselage structure.

Cyclic and collective control continuity was verified. Damage to the tail rotor controls corresponded with tailboom damage. The tail rotor blades exhibited impact damage with bent spars or tear to the blade skin. The main rotor blade damage varied in severity and included blades being bent, chordwise wrinkling, leading/trailing edge and tip cap damage. One blade was fractured at the inboard end just outboard of the root fitting. Drive system continuity was verified. The main rotor system hub assembly and components displayed typical damage from main rotor blades contacting the tailboom during the hard landing. There was visible damage to the hub upper and lower shoe, feather bearings, pitch change housings, and droop stops. Damage was consistent with the excessive blade flapping and lead-lag excursions of the main rotor from sudden stoppage at low rotor rpm without engine power.

The fuel cells were near full and there was no reported fuel spillage at the accident site. A vacuum check from the fuel inlet line at the fuel pump to the fuel shut off valve was satisfactorily completed. The fuel cells were drained using the maintenance fuel pump located in the fuel cell and the left fuel cell cover removed. The fuel cells appeared undamaged and the fuel removed looked visually clean. The maintenance fuel pump was removed and the fuel inlet ports and fuel tank sump was inspected. No contamination or blockage was found. Inspection of the fuel line plumbing and fittings did not identify any damage or discrepancies.

Visual inspection found the engine and related systems sustained only minimal external damage. There was visible impact damage to the engine's outer combustor case, fuel nozzle and fuel line. The fuel nozzle was cleaned just prior to the accident flight and the fuel line was reported loose at the accident site, however the fuel line also exhibited impact damage. The engine manufacturer reported that past experience has shown that b-nuts that are not fully torqued on the fuel nozzle may not affect normal engine operation, and that properly torqued b-nuts don't come loose under normal operating conditions.

There was no obvious evidence of fuel leakage in the engine area. Inspection of the engine mounts found the aft engine mount legs bent at the turn buckles. The left and right engine side mounts appeared undamaged. There were contact marks on the firewall from the engine driveshaft indicating movement of the engine during the crash sequence. With electrical power applied the engine trim switch (N2) was functional when tested. Some pneumatic and fuel line b-nuts had torque paint that was broken or misaligned. A check of air, fuel and oil lines found them to be at least hand tight. A check of the throttle and governor controls was completed with no discrepancies noted. The engine was removed from the airframe for further examination and testing.

Examination and functional testing of the engine was conducted on January 20, 2015 at Aeromaritime America Inc., located on Falcon Field in Mesa, Arizona. Representatives from the airframe and engine manufacturers were present and oversight was provided by a FAA inspector. The damaged outer combustion case, combustion liner and fuel nozzle were replaced with serviceable items. Except for the fuel line to the fuel nozzle and the fuel supply line at the fuel control, no other fuel or pneumatic lines were altered prior to the test cell run. The engine was run on the test cell and no operational discrepancies were noted, with the engine producing rated power. After the test cell run, a pneumatic leak check was performed on the pneumatic portion of the fuel control system. The scroll to Pc filter line was disconnected and 30 psi air pressure was applied to the Pc filter. A soap solution was used to check all fittings and lines in the system for leaks. The Pg accumulator line connection showed a formation of small air bubbles indicating a leak. The line was tightened with wrenches and the leak stopped. All the other lines were checked with a torque wrench and found to have 65 inch-pound or greater torque.

Two external fuel lines were examined by the NTSB investigator-in-charge, one line that had orange fire sleeve attached from end to end that connected the engine to the firewall, and the other, a black hose connecting the firewall to the fuel shut off valve. The fuel lines were examined visually using a borescope, and by sectioning the lines into segments. Additionally, the fuel filter was examined and found to be clear of debris. The examination of these items revealed that they were in very good functional condition with no anomalies identified.

A fuel sample was taken from the fuel line that runs between the firewall and the shutoff valve. The sample was a clear fluid with a petroleum odor and had a small amount of white particulate sediment. The sample was analyzed by a third party. The sample was examined using ASTM D2887 (Standard Test Method for Boiling Range Distribution of Petroleum Fractions by Gas Chromatography) to determine the type of fuel in the sample. The distillation results for this sample were consistent with jet fuel (Jet-A). In addition, the visible particulates were tested using ASTM D5185 (Standard Test Method for Multi-element Determination of Used and Unused Lubricating Oils and Base Oils by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES)). The results were sodium (Na) 82.8 mg/kg, zinc (Zn) 4.9 mg/kg, iron (Fe) 5.4 mg/kg, and magnesium (Mg) 6.7 mg/kg. The elements found are commonly occurring elements found in many things, including soil.

The most recent weight and balance was dated April 3, 2014, showed the helicopter empty weight as 1975.22 pounds. At the time of the accident the gross weight was calculated to be 2,810 lbs. It was determined that the helicopter had been operating within the published weight and balance limits. Maintenance records and a witness statement show that a 100-hour airframe and engine inspection had been completed on December 31st but had not been signed off as completed by maintenance personnel before the pilots took the helicopter.

NTSB Probable Cause

A total loss of engine power during cruise flight for reasons that could not be determined because postaccident examination and testing did not reveal any anomalies that would have precluded normal operation.