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ASN Wikibase Occurrence # 205654
Last updated: 19 June 2021
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Time:16:43 LT
Type:Silhouette image of generic H64 model; specific model in this crash may look slightly different
Boeing AH-64D Apache Longbow
Owner/operator:Japan Ground Self-Defense Force
Registration: 74502
MSN: JP002
Fatalities:Fatalities: 2 / Occupants: 2
Other fatalities:0
Aircraft damage: Written off (damaged beyond repair)
Location:Chiyoda, Kanzaki city, Saga prefecture -   Japan
Phase: En route
Departure airport:Metabaru Airbase (RJDM)
Destination airport:Metabaru Airbase (RJDM)
A combat helicopter AH-64D of Japan Ground Self-Defense Force crashed in a house near a school, located 6km southwest of Metabaru Airbase (RJDM). The Apache dived from the nose while flying westbound, during a test flight seven minutes after takeoff. Eyewitness reports that the main rotor was separated in pieces inflight. The debris were spread for 300 meters east of the crash site, and 550 meters wide. The crashed house was consumed by post impact fire, and seven other building received some damages like hole by penetrating debris or clinging grease. A resident, 11 years old school girl, was slightly bruised on her right leg. One of the occupants was found beside the wreckage and received fatal injury, while a part of the body of the other occupant was located under the wreckage next morning. The AH-64D had just finished 50-hour regular maintenance from 18th January to 4th February, 2018, along with a replacement of the main rotor head which should be done every 1750 flight hours. The Apache Longbow had experienced 1733 flight hours before the crash. This perticular replacement was the first time for the accident helicopter, and the eighth (initially reported as third) time for thirteen AH-64D's operated by JGSDF. The maintenance data recorder was retrieved the next day with substantial damage. JGSDF launched an investigation. On 7th February, the main rotor head with two blades and the mast was found in the main crash site, however, the third blade were located in a stream 500 meters apart from the main rotor head. The last blade was found 300 meters apart on 9th February. Latter two blades separated were connected with parts of the main rotor head, which suggest inflight disintegration of the main rotor head. On 14th February, it was revealed that the main rotor head installed in the maintenance just before the accident was not new. It had been used by another AH-64D of JGSDF for 845 flight hours until April 2010, removed due to wear and vibration, and repaired in U.S. before installation to the accident AH-64D.

On 28th May 2018, an interim report was released by JGSDF. It states as follows:
The cause of the accident was neither the pilot error nor the maintenance error by the ground crew. The accident originated from inflight breaking of the outboard bolt which connects No.4 main rotor blade and the strap pack. It resulted in 6mm gap between the outboard bolt and the outboard nut, and subsequently gaps between laminae forming the strap pack. Due to imbalanced centrifugal forces, laminae broke apart. Then, No.4 main rotor separated from the main rotor head, which resulted in loss of the lift. Investigation to clear the initial break of the outboard bolt is still going on beyond 4-month limit in the regulation.

Weather reports at Metabaru Airbase (accident time 16:43LT/07:43 UTC):
SPECI RJDM 050525Z 26012G26KT 9999 -SHSN FEW025 SCT030 BKN045
02/M08 Q1023 RMK 1CU025 4CU030 6CU045 A3021 5000N=
SPECI RJDM 050810Z 29007KT 2500 -SHSN FEW010 BKN020 00/M07
Q1023 RMK 1CU010 7CU020 A3022=




Revision history:

05-Feb-2018 09:15 isamuel Added
05-Feb-2018 14:02 Iceman 29 Updated [Total fatalities, Source, Embed code, Narrative, Photo, ]
05-Feb-2018 15:33 isamuel Updated [Registration, Other fatalities, Location, Departure airport, Destination airport, Source, Narrative]
05-Feb-2018 16:33 Geno Updated [Cn, Source]
05-Feb-2018 19:47 Iceman 29 Updated [Aircraft type, Source]
06-Feb-2018 08:32 Iceman 29 Updated [Embed code]
06-Feb-2018 08:41 isamuel Updated [Source, Narrative]
06-Feb-2018 16:56 isamuel Updated [Source, Narrative]
07-Feb-2018 00:17 Iceman 29 Updated [Embed code]
07-Feb-2018 10:57 isamuel Updated [Source, Narrative]
08-Feb-2018 11:31 Iceman 29 Updated [Source]
09-Feb-2018 14:05 isamuel Updated [Source, Narrative]
13-Feb-2018 09:42 Iceman 29 Updated [Embed code]
14-Feb-2018 08:29 isamuel Updated [Source, Embed code, Narrative]
14-Feb-2018 13:07 isamuel Updated [Source, Narrative]
29-May-2018 09:07 isamuel Updated [Source, Narrative]

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