ASN Wikibase Occurrence # 89948
Last updated: 30 September 2014
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Date:09-FEB-2011
Time:~2:15 p.m.
Type:Silhouette image of generic DH8C model; specific model in this crash may look slightly different
de Havilland Canada DHC-8-311
Owner/operator:Air Nelson
Registration: ZK-NEQ
C/n / msn: 636
Fatalities:Fatalities: 0 / Occupants: 44
Other fatalities:0
Airplane damage: Minor
Location:Blenheim Airport (NZWB) -   New Zealand
Phase: Landing
Nature:Domestic Scheduled Passenger
Departure airport:NZHN
Destination airport:NZWN
Narrative:
Air Nelson ( a subsidiary of Air New Zealand ) flight NZ8309 from Hamilton to Wellington was diverted to Blenheim NZWB for a landing with an unsafe undercarriage.

Prior to taking off from Hamilton, the nosewheel steering malfunctioned because an "inhibit switch" in the cockpit was faulty. The faulty switch caused a loss of hydraulic pressure to the nosewheel steering. The nosewheel steering system was considered non-essential, so in accordance with the approved Minimum Equipment List, the aeroplane departed Hamilton with the system inoperative. The trip towards Wellington was uneventful.

The nosewheel steering hydraulic power came from the extend side of the landing gear hydraulic system. On the approach to Wellington, none of the landing gear extended when it was selected down. The pilots carried out a go-around to give them time to perform the relevant procedures provided in a Quick Reference Handbook (QRH). The Q300 was fitted with an alternative system for lowering the landing gear when the normal system failed. The "Alternate Gear Extension" procedure succeeded in getting the main landing gear to extend, but not the nose landing gear. That remained locked in its retracted position.

There was nothing mechanically wrong with the alternate landing gear extension system. The nose landing gear did not extend because the pilots did not pull hard enough on the handle that should have released the uplock. If the uplock had released, the nose landing gear would have lowered under gravity and locked down.

The pilots decided to divert to Woodbourne Aerodrome and to land with the nose landing gear retracted. No-one was injured in the landing. The damage to the aeroplane was confined to the area around the nose landing gear and the lower forward fuselage.

The Minimum Equipment List appeared to have considered the operational consequences only of allowing a Q300 to depart with inoperative nosewheel steering. The link between a failure of the nosewheel steering and a potential failure in the hydraulic system, which would affect the landing gear, did not appear to have been considered. The manufacturer has since amended the Minimum Equipment List to require a check of the hydraulic system pressure before allowing a departure with the nosewheel steering inoperative.

The operator's pilots were not made aware through their training of how hard one had to pull the handle to release the nose landing gear uplock. A much lesser pull was required when practising the procedure in the operator's flight simulator and the Alternate Gear Extension procedure did not, at the time, give any guidance as to the force required.

Sources:
http://www.taic.org.nz/ReportsandSafetyRecs/AviationReports/tabid/78/ctl/Detail/mid/482/InvNumber/2011-002/Page/0/language/en-US/Default.aspx?SkinSrc=[G]skins/taicAviation/skin_aviation
http://www.3news.co.nz/Plane-preparing-to-make-emergency-landing-in-Blenheim/tabid/423/articleID/197744/Default.aspx
http://www.stuff.co.nz/national/4636721/Emergency-landing-at-Blenheim
http://www.stuff.co.nz/dominion-post/4636721/Emergency-landing-at-Blenheim



Auckland International 7Nov2008

Revision history:

Date/timeContributorUpdates
08-Feb-2011 21:38 angels one five Added
08-Feb-2011 22:04 angels one five Updated [Registration, Source]
09-Feb-2011 01:54 turtle Updated [Registration, Source]
09-Feb-2011 05:30 flyernzl Updated [Cn]
09-Feb-2011 13:17 j28gulfstream Updated [Aircraft type]
09-Feb-2011 14:04 angels one five Updated [Narrative]
08-Feb-2013 11:21 harro Updated [Operator, Location, Source, Narrative]
Number of views: 1159

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