Norways first AW101 on its side

[dangermouse]

Nosewheel steering design requirements for 101 (info for SASless)

The NWS system operates the way it does due to the RN requirement for the aircraft to be recovered into a ships hangar with no-one on deck (itself a pretty tough requirement to meet on a frigate in the north atlantic). Based on Lynx experience the RN aircraft is required to have a deck lock (harpoon) at the centre of rotation of the aircraft, that engages into a grid on the deck, the aircraft is then orientated towards the hangar by spinning around the deck lock with the nosegear at 90 degs (castored). The Lynx manages this by having the main gear orientated outboard with a free castoring nosegear, this works fine but the gear orientation has to be carried out by groundcrew and when locked outboard prevents any ground handing (the Lynx was not required move into the hangar independently, the Merlin was). This was deemed unworkable on the 101 given the size of the aircraft and the need to also have the capability to enter the hangar (mainwheels must remain fore/aft) with no one on the deck. Therefore a powered castoring nosegear system was selected. This moves the gear to 90 degs so the aircraft can be orientated correctly to allow the automatic deck handling shuttles to engage the u/c legs to pull the aircraft into the hangar.

Now as you have a powered castoring nosegear it makes sense to use some of the capability to allow ground steering to be carried out, the NWS has 50 degs of movement either side of fore/aft to allow steering during ground taxiing to take place. There are speed limits for using this system and for higher speeds either use of differential main gear braking or the tail rotor can be used to control heading. Obviously disengaging heading hold is a good idea when ground handling, FRCs include the appropriate limits and warnings which have been mentioned previously.

So as the RN aircraft uses that system specifically to meet a basic RN requirement, for commonality across 101 variants they all have it.

The strut change mentioned by davigal is specific to naval variants of the 101 and allows the main gear damping value to be selected from 'soft' to 'hard' to prevent excessive aircraft motion when embarked on ships, it is manually selectable from outside the aircraft and the status is included in the preflight walkaround checks. I suspect that the Norway aircraft not being a naval variant doesn't have this option in any case

In any case I don't think we can imply anything as a cause of the incident as the nosegear is obviously orientated fore/aft in the photos.