ASN Wikibase Occurrence # 186952
This information is added by users of ASN. Neither ASN nor the Flight Safety Foundation are responsible for the completeness or correctness of this information.
If you feel this information is incomplete or incorrect, you can submit corrected information.
| Date: | Wednesday 4 May 2016 |
| Time: | 10:02 |
| Type: |  MD Helicopters MD 500E (369E) |
| Owner/operator: | Rotor Blade LLC |
| Registration: | N629JK |
| MSN: | 0542E |
| Year of manufacture: | 1999 |
| Total airframe hrs: | 7688 hours |
| Engine model: | Rolls Royce M250-C20B |
| Fatalities: | Fatalities: 1 / Occupants: 1 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Manitowoc County NW of Maple Grove, WI -
 United States of America
|
| Phase: | Manoeuvring (airshow, firefighting, ag.ops.) |
| Nature: | Cargo |
| Departure airport: | Reedsville, WI |
| Reedsville, WI | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
The helicopter was being used to transport personnel and equipment in support of a power line construction project. The helicopter departed the landing zone (LZ) and transported two linemen from one power line tower to another using a 50 ft long line (i.e. Human External Cargo). When the linemen detached from the long line, the helicopter proceeded to the east where it hovered for 2 to 3 minutes. The linemen requested that the helicopter return to the tower to pick up equipment and then return to the LZ. The helicopter approached the tower, and, when the long line was nearing their reach, the linemen noticed the helicopter's sound change, and it descended suddenly. The helicopter veered to the right away from the tower, and the main rotor blades slowed noticeably as the helicopter descended into the trees and impacted terrain. The linemen climbed down from the tower and heard the helicopter's engine still producing noise, so one of them pulled the emergency fuel shutoff valve and turned the battery off.
A postaccident examination of the helicopter revealed damage to the main rotor blades and main rotor hub consistent with sudden stoppage at low rotor rpm. The tail rotor exhibited damage consistent with no rotation during impact. The engine was removed from the airframe and connected to an engine test stand for a functional test, but it would not start after several attempts. The power turbine governor (PTG) was removed, and its main drive shaft was found fractured. The original PTG was replaced with a new PTG. With the new PTG installed, the engine started normally, produced rated horsepower, and met production test specifications with no anomalies noted.
Examination of the PTG revealed that a portion of the drive shaft remained embedded in the spindle of the spool bearing assembly. The fracture surface features of the shaft were consistent with overstress. The internal elements of the spool bearing assembly were seized and would not rotate. The ball bearings and spacers were found coated with voluminous, powdery, black particulate consistent with oxidized metallic wear debris, and no grease was observed. The ball retainers were fragmented, the inner surfaces were found coated with a powdery, black particulate consistent with oxidized metallic wear debris, and no grease was observed. The inner bearing surfaces were rough and frosted, consistent with three-body abrasive wear. The examination indicated that the fractured PTG drive shaft was the result of a spool bearing that seized due to a lack of lubrication.
In 2008, a service bulletin (SB) and commercial engine bulletin (CEB) were issued by PTG and engine manufacturers, respectively, that called for replacement of the dual-spool bearing, the type installed in the accident PTG, with a single-spool bearing. The dual-spool bearing had experienced 23 previous failures that had led to either engine oscillations, uncommanded engine acceleration, or a loss of engine power. Although the SB and CEB called for replacement of the accident PTG's dual-spool bearing not later than 750 hours after the PTG was installed new, the accident PTG had accumulated 1,048.7 hours since new when the accident occurred, and the SB and CEB had not been completed. As stated in the operator's Federal Aviation Administration (FAA) approved operations specifications, the operator was required to comply with FAA Airworthiness Directives but was not required to comply with manufacturer's service bulletins. It is likely that had the SB and CEB been completed, the PTG would not have failed and the engine would not have lost power.
Probable Cause: The failure of the power turbine governor's dual-spool bearing due to a lack of lubrication, which resulted in a complete loss of engine power and subsequent impact with terrain.
Accident investigation:
 |
|
Sources:
http://aerossurance.com/helicopters/md369e-engine-unmodified/
NTSB
FAA register: http://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?nNumberTxt=629JK
History of this aircraft
Other occurrences involving this aircraft
| 19 August 2006 | N554CP | Columbus City Police | 0 | Columbus, OH | |
sub |
| Law Enforcement | ||||||
Location
Media:
#OTD 2016: A fatal #accident approaching powerlines to collect two electricity linesman by longline that demonstrates the criticality of assessing recommended service bulletins.https://t.co/QjdZw4KYC4 #flightsafety #aviationsafety #helicopter #maintenance #airworthiness pic.twitter.com/zFaz66b5m0
— Aerossurance (@Aerossurance) May 4, 2021
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 05-May-2016 01:11 | Geno | Added |
| 05-May-2016 06:46 | harro | Updated [Aircraft type] |
| 06-May-2016 07:45 | Aerossurance | Updated [Time, Nature, Source, Narrative] |
| 09-May-2016 13:36 | Aerossurance | Updated [Registration, Cn, Source] |
| 12-May-2016 15:38 | Aerossurance | Updated [Source, Narrative] |
| 12-May-2016 15:39 | Aerossurance | Updated [Departure airport, Narrative] |
| 21-Dec-2016 19:30 | ASN Update Bot | Updated [Time, Damage, Category, Investigating agency] |
| 19-Aug-2017 14:30 | ASN Update Bot | Updated [Time, Cn, Nature, Departure airport, Destination airport, Source, Narrative] |
| 19-Aug-2017 14:31 | ASN Update Bot | Updated [Source] |
| 19-Aug-2017 14:35 | harro | Updated [Nature, Source] |
| 04-May-2021 06:52 | Aerossurance | Updated [Nature, Source, Embed code, Narrative] |
Corrections or additions? ... Edit this accident description
The Aviation Safety Network is an exclusive service provided by:
Quick Links:
| ASN Home | Send Correction / Feedback |
| FSF Home | Disclaimer | Copyright |
| Contact Us | Privacy Policy |
| Press / Media |
CONNECT WITH US:
©2024 Flight Safety Foundation