Wow, now I'm sober, I read back my posting and it doesn?t make sense to me, let alone anyone else. I didn?t mean it was hydraulically levelled out because this would put the air/ground sense into ground. I was trying to illustrate the fact the tilt angle isn?t as pronounced as a 747.
Right. What I meant to say was unlike some aircraft the 767 doesn?t have any significant obstructions in the wheel well that require the gear to be in a specific position.
I believe the gear is not tilted to fit in the bay; it is tilted for other reasons. The gear pivot in the wing (trunnion) is parallel to the fuselage centre line (buttock line zero). The undercarriage leg is approximately vertical so when the gear is retracted I believe it is perpendicular to the fuselage centre line. If this is correct then there is no reason why the bogie has to be tilted because it goes into a rectangular bay with no obstructions in it like hydraulic reservoirs.
So why do I think the bogies are tilted for retraction.
The wheels and tyres have a great deal of inertia which needs to be controlled. If there was no truck tilt actuator the bogie would flap around violently. If the bogie was held level it would need substantial damping in both directions. Therefore it is much easier to tilt the gear as far as it will go in one direction with a truck tilt actuator. By doing this you control the bogie in the simplest manner possible and you know what position it is in when it is stowed so you can design the undercarriage bay around it. This is why I believe the gear is not tilted to fit in the bay, it is tilted for other reasons and it is convenient that it fits the bay.
As far as gear sensors are concerned the 767 there are sensors on the bogie, the downlocks and the doors.
The near/far sensor on the bogie to sense air/ground. If the truck is level then it is on the ground (the aircraft weight is overcoming the 3000 psi trying to tilt it). If the aircraft is on the ground a solenoid on the landing gear handle prevents it from being moved into the retract position.
The downlock sensors give the three green gear locked lights on the dashboard.
The door switches sense the body door position either open or closed (gear not up as the gear rests on the door in flight.)
The million dollar question that I can?t answer is why the 767 bogies tilt forwards whereas most bogies tilt backwards.
The Aircraft Maintenance manuals are written to be read by someone whose native language is not always English. They may not tell the whole truth but tell things in a manner to be as clear as possible, hence you get some fantastic statements such as this in the main wheel installation procedure AMM 32-45-01/409 para 3F - 4b ?? It is important to apply torque with only one hand because application of more than 5 foot-pounds of torque can CAUSE DAMAGE TO
A PART THAT IS
NOT ALREADY DAMAGED.