What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
On November 20, 2018, at approximately 11:31 CST, N96AE, a BHT-206-L1, s/n 45751, located at air evac EMS, inc. base AE-018 in Salem, Missouri, experienced an engine flameout (reported as uncommanded) shortly after entering autorotation. The autorotation manuever was purposefully performed as part of a planned operational system check, used to determine autorotation rotor speed. The autorotation check was performed as a typically required check in response to a pilot-reported ground bounce / vertical vibration.
Air evac EMS, inc. thoroughly inspected the aircraft in attempt to determine cause of the flame out. The checks and the conditions they noted are as follows:
1. The aircraft was found with the fuel valve off, the throttle off, both boost pump breakers closed, and 450 pounds of indicated fuel.
2. There were no fuel leaks noted from the engine compartment or from the airframe.
3. A fuel sample was taken and no water was found in the fuel.
4. All engine connections were checked for tightness and found to be tight.
5. The engine throttle rigging was checked and appeared to be correct, hitting high stop, low stop, and lining up properly with the rig pin hole at idle.
6. The engine fuel nozzle line was removed and the engine was motored. Fuel came out of the nozzle at the expected rate with the throttle open and stopped when the throttle was closed.
The maintenance crew performed trouble-shooting of the aircraft, examining the engine, fuel system, fuel cell, etc., and could not replicate the engine flame-out occurrence nor determine a cause.
Air evac EMS, inc decided to remove the engine and sent it to a test cell for further evaluation. The results were not available at the time of the submital of this report.
On 12-19-2018, aerial tested engine s/n cae 900093 i/a/w the overhaul manual and could not duplicate the flame out.
During the first test aerial had the fuel control pointer at the 40° mark on the quadrant. Aerial then lowered the pointer to the max allowable position of 5/64 allowed per the operation and maintenance manual. Aerial preformed serval deceleration and acceleration from takeoff to idle. Aerial was still not able to duplicate a flame out. Aerial then continued to lower the pointer on the quadrant and preformed serval deceleration and acceleration till aerial was able to duplicate the flame out. The flame out was duplicated with the pointer ¼ below the 40° mark on the quadrant. This is well below the operation and maintenance manual limits and aerial is not suggesting that the engine was rigged this way.
The engine only has 319 cycles remaining on the 1st and 2nd stage wheels. The bleed valve has 77.4 hours remaining till due overhaul. The outer combustion case would require CEB-72-3308
As the FAA filed it
ON NOVEMBER 20, 2018, AT APPROXIMATELY 11:31 CST, N96AE, A BHT-206-L1, S/N 45751, LOCATED AT AIR EVAC EMS, INC. BASE AE-018 IN SALEM, MISSOURI, EXPERIENCED AN ENGINE FLAMEOUT (REPORTED AS UNCOMMANDED) SHORTLY AFTER ENTERING AUTOROTATION. THE AUTOROTATION MANUEVER WAS PURPOSEFULLY PERFORMED AS PART OF A PLANNED OPERATIONAL SYSTEM CHECK, USED TO DETERMINE AUTOROTATION ROTOR SPEED. THE AUTOROTATION CHECK WAS PERFORMED AS A TYPICALLY REQUIRED CHECK IN RESPONSE TO A PILOT-REPORTED GROUND BOUNCE / VERTICAL VIBRATION.
AIR EVAC EMS, INC. THOROUGHLY INSPECTED THE AIRCRAFT IN ATTEMPT TO DETERMINE CAUSE OF THE FLAME OUT. THE CHECKS AND THE CONDITIONS THEY NOTED ARE AS FOLLOWS:
1. THE AIRCRAFT WAS FOUND WITH THE FUEL VALVE OFF, THE THROTTLE OFF, BOTH BOOST PUMP BREAKERS CLOSED, AND 450 POUNDS OF INDICATED FUEL.
2. THERE WERE NO FUEL LEAKS NOTED FROM THE ENGINE COMPARTMENT OR FROM THE AIRFRAME.
3. A FUEL SAMPLE WAS TAKEN AND NO WATER WAS FOUND IN THE FUEL.
4. ALL ENGINE CONNECTIONS WERE CHECKED FOR TIGHTNESS AND FOUND TO BE TIGHT.
5. THE ENGINE THROTTLE RIGGING WAS CHECKED AND APPEARED TO BE CORRECT, HITTING HIGH STOP, LOW STOP, AND LINING UP PROPERLY WITH THE RIG PIN HOLE AT IDLE.
6. THE ENGINE FUEL NOZZLE LINE WAS REMOVED AND THE ENGINE WAS MOTORED. FUEL CAME OUT OF THE NOZZLE AT THE EXPECTED RATE WITH THE THROTTLE OPEN AND STOPPED WHEN THE THROTTLE WAS CLOSED.
THE MAINTENANCE CREW PERFORMED TROUBLE-SHOOTING OF THE AIRCRAFT, EXAMINING THE ENGINE, FUEL SYSTEM, FUEL CELL, ETC., AND COULD NOT REPLICATE THE ENGINE FLAME-OUT OCCURRENCE NOR DETERMINE A CAUSE.
AIR EVAC EMS, INC DECIDED TO REMOVE THE ENGINE AND SENT IT TO A TEST CELL FOR FURTHER EVALUATION. THE RESULTS WERE NOT AVAILABLE AT THE TIME OF THE SUBMITAL OF THIS REPORT.
ON 12-19-2018, AERIAL TESTED ENGINE S/N CAE 900093 I/A/W THE OVERHAUL MANUAL AND COULD NOT DUPLICATE THE FLAME OUT.
DURING THE FIRST TEST AERIAL HAD THE FUEL CONTROL POINTER AT THE 40° MARK ON THE QUADRANT. AERIAL THEN LOWERED THE POINTER TO THE MAX ALLOWABLE POSITION OF 5/64 ALLOWED PER THE OPERATION AND MAINTENANCE MANUAL. AERIAL PREFORMED SERVAL DECELERATION AND ACCELERATION FROM TAKEOFF TO IDLE. AERIAL WAS STILL NOT ABLE TO DUPLICATE A FLAME OUT. AERIAL THEN CONTINUED TO LOWER THE POINTER ON THE QUADRANT AND PREFORMED SERVAL DECELERATION AND ACCELERATION TILL AERIAL WAS ABLE TO DUPLICATE THE FLAME OUT. THE FLAME OUT WAS DUPLICATED WITH THE POINTER ¼ BELOW THE 40° MARK ON THE QUADRANT. THIS IS WELL BELOW THE OPERATION AND MAINTENANCE MANUAL LIMITS AND AERIAL IS NOT SUGGESTING THAT THE ENGINE WAS RIGGED THIS WAY.
THE ENGINE ONLY HAS 319 CYCLES REMAINING ON THE 1ST AND 2ND STAGE WHEELS. THE BLEED VALVE HAS 77.4 HOURS REMAINING TILL DUE OVERHAUL. THE OUTER COMBUSTION CASE WOULD REQUIRE CEB-72-3308