737-800: Change in hydraulic reservoir quantity on landing gear retraction
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Grounded 27 - would you like to give me a specific type that does not have a pressurised extension of the landing gear? In a working life of nearly 50 years maintaining a variety of aircraft from piper Aztec to Boeing 747 I have never seen a retractable gear that is not powered in both directions. I think your knowledge of aircraft hydraulic systems is that of an amateur.
aaa0808,
"I agree that extension can be done by gravity alone as well and is done during non-normal conditions.
But that doesnt give us any control over the movement of the gear and might lead to its free fall, suddenly increasing drag and even damaging the mechanical structure"
Does'nt matter if the gear is extended by hydraulics or freefall, it still creates the same amount of drag. But possible structural damage will occur if the gear is extended (wether by hydraulics or freefall) in a gear OVERSPEED condition.
McHale.
"I agree that extension can be done by gravity alone as well and is done during non-normal conditions.
But that doesnt give us any control over the movement of the gear and might lead to its free fall, suddenly increasing drag and even damaging the mechanical structure"
Does'nt matter if the gear is extended by hydraulics or freefall, it still creates the same amount of drag. But possible structural damage will occur if the gear is extended (wether by hydraulics or freefall) in a gear OVERSPEED condition.
McHale.
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@bcgallacher:
Whoa, no need to lash out at people... One of those aircraft is the 777 - Gear extension only releases the uplocks hydraulically to let the gear free fall (metered by a flow restrictor in the retraction actuator). The side and drag braces on the main gears are also hydraulically overcentered to lock the gear down, but they will extend and lock without pressure as well during a manual extension. (Ref AMM 32-32-00-001)
Whoa, no need to lash out at people... One of those aircraft is the 777 - Gear extension only releases the uplocks hydraulically to let the gear free fall (metered by a flow restrictor in the retraction actuator). The side and drag braces on the main gears are also hydraulically overcentered to lock the gear down, but they will extend and lock without pressure as well during a manual extension. (Ref AMM 32-32-00-001)
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The fact that it is called a "retract actuator' on the 777 kinda gives you a clue.. 
Perhaps we can put this discussion to bed now?
Perhaps we can put this discussion to bed now?
Last edited by Jet II; 13th Feb 2016 at 14:14.
