What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
On 06/01/2023 at approximately 1825 EDT, a Bell 407 was performing firefighting operations when the aircraft experienced abnormal vibrations. The mechanical abnormality resulted with the pilot jettisoning the “bambi” bucket and performed an emergency landing in a clearing adjacent to lost lake.
On 06/01/2023 the flight originated from hanley field (5Y7) and was conducted in visual meteorological conditions. The purpose of the flight was performing firefighting operations in the vicinity of lost lake. The pilot stated he had performed approximately 15 bucket dumps prior to the event. The pilot stated “I flew continuously for roughly 1.5HRS and started bucket work towards the end of that period. Out of the dip, within 200 ft of the ground, a strong, higher frequency vibration occurred that persisted. I jettisoned the bucket after a few seconds and started an approach to the only suitable landing area in the near vicinity. As I made an approach to the lz the vibrations intensified until touchdown. From the onset of vibration to landing I would estimate the duration to be less than 30 seconds. After touchdown, the aircraft began to settle towards the tail as it was located in a bog/swamp.” additionally the pilot stated during the shutdown the aircraft engine would not stop operation via the standard process and the pilot turned off the fuel pump to shut down the engine. The aircraft landed safely without damage and no reported injuries.
06/02/2023 The aircraft was inspected for damage. No damage was found or any abnormal maintenance findings during the initial maintenance assessment. The aircraft was transported by another aircraft via “sling load” to a maintenance facility for further evaluation.
Damage is as follows: no damage found
The maintenance team noted the engine was previously overhauled on 05/21/2023. The maintenance team performed extensive inspections, in-flight operational checks, and preventive maintenance checks. The maintenance team found minor irregularities with the collective pitch transducer, the part was replaced as a precaution, but was not known to be the specific cause of the engine shutdown failure. The following maintenance action dates associated with work order number 5027:
• 6/4/2023, Maintenance actions contain the investigative inspections the maintenance team performed
• 6/9/2023, Maintenance actions contain the completions of scheduled maintenance/ preventive maintenance
• 6/13/2023 Additional maintenance actions performed.
The maintenance team could not duplicate the specific abnormalities as noted by the pilot.
As the FAA filed it
ON 06/01/2023 AT APPROXIMATELY 1825 EDT, A BELL 407 WAS PERFORMING FIREFIGHTING OPERATIONS WHEN THE AIRCRAFT EXPERIENCED ABNORMAL VIBRATIONS. THE MECHANICAL ABNORMALITY RESULTED WITH THE PILOT JETTISONING THE “BAMBI” BUCKET AND PERFORMED AN EMERGENCY LANDING IN A CLEARING ADJACENT TO LOST LAKE.
ON 06/01/2023 THE FLIGHT ORIGINATED FROM HANLEY FIELD (5Y7) AND WAS CONDUCTED IN VISUAL METEOROLOGICAL CONDITIONS. THE PURPOSE OF THE FLIGHT WAS PERFORMING FIREFIGHTING OPERATIONS IN THE VICINITY OF LOST LAKE. THE PILOT STATED HE HAD PERFORMED APPROXIMATELY 15 BUCKET DUMPS PRIOR TO THE EVENT. THE PILOT STATED “I FLEW CONTINUOUSLY FOR ROUGHLY 1.5HRS AND STARTED BUCKET WORK TOWARDS THE END OF THAT PERIOD. OUT OF THE DIP, WITHIN 200 FT OF THE GROUND, A STRONG, HIGHER FREQUENCY VIBRATION OCCURRED THAT PERSISTED. I JETTISONED THE BUCKET AFTER A FEW SECONDS AND STARTED AN APPROACH TO THE ONLY SUITABLE LANDING AREA IN THE NEAR VICINITY. AS I MADE AN APPROACH TO THE LZ THE VIBRATIONS INTENSIFIED UNTIL TOUCHDOWN. FROM THE ONSET OF VIBRATION TO LANDING I WOULD ESTIMATE THE DURATION TO BE LESS THAN 30 SECONDS. AFTER TOUCHDOWN, THE AIRCRAFT BEGAN TO SETTLE TOWARDS THE TAIL AS IT WAS LOCATED IN A BOG/SWAMP.” ADDITIONALLY THE PILOT STATED DURING THE SHUTDOWN THE AIRCRAFT ENGINE WOULD NOT STOP OPERATION VIA THE STANDARD PROCESS AND THE PILOT TURNED OFF THE FUEL PUMP TO SHUT DOWN THE ENGINE. THE AIRCRAFT LANDED SAFELY WITHOUT DAMAGE AND NO REPORTED INJURIES.
06/02/2023 THE AIRCRAFT WAS INSPECTED FOR DAMAGE. NO DAMAGE WAS FOUND OR ANY ABNORMAL MAINTENANCE FINDINGS DURING THE INITIAL MAINTENANCE ASSESSMENT. THE AIRCRAFT WAS TRANSPORTED BY ANOTHER AIRCRAFT VIA “SLING LOAD” TO A MAINTENANCE FACILITY FOR FURTHER EVALUATION.
DAMAGE IS AS FOLLOWS: NO DAMAGE FOUND
THE MAINTENANCE TEAM NOTED THE ENGINE WAS PREVIOUSLY OVERHAULED ON 05/21/2023. THE MAINTENANCE TEAM PERFORMED EXTENSIVE INSPECTIONS, IN-FLIGHT OPERATIONAL CHECKS, AND PREVENTIVE MAINTENANCE CHECKS. THE MAINTENANCE TEAM FOUND MINOR IRREGULARITIES WITH THE COLLECTIVE PITCH TRANSDUCER, THE PART WAS REPLACED AS A PRECAUTION, BUT WAS NOT KNOWN TO BE THE SPECIFIC CAUSE OF THE ENGINE SHUTDOWN FAILURE. THE FOLLOWING MAINTENANCE ACTION DATES ASSOCIATED WITH WORK ORDER NUMBER 5027:
• 6/4/2023, MAINTENANCE ACTIONS CONTAIN THE INVESTIGATIVE INSPECTIONS THE MAINTENANCE TEAM PERFORMED
• 6/9/2023, MAINTENANCE ACTIONS CONTAIN THE COMPLETIONS OF SCHEDULED MAINTENANCE/ PREVENTIVE MAINTENANCE
• 6/13/2023 ADDITIONAL MAINTENANCE ACTIONS PERFORMED.
THE MAINTENANCE TEAM COULD NOT DUPLICATE THE SPECIFIC ABNORMALITIES AS NOTED BY THE PILOT.
Other reports on N20BH · 1
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