ALT Gear Handle?

[mytai01]

Is the ALT GEAR handle going to be made to work at some point? Or, is it not operational in the real aircraft anymore?

[mvsgas]

IRL, is the only way to deploy the landing gear without hydraulic system B pressure. EPU only power A system. So IRL, it will always be that way until the completely change the way hydraulics work in the F-16.

 

Whether it will ever be implemented in DCS or not, I do not know

[b0bl00i]

This would be awesome

 

[Carbon715]

On 9/8/2021 at 9:30 PM, mvsgas said:

IRL, is the only way to deploy the landing gear without hydraulic system B pressure. EPU only power A system. So IRL, it will always be that way until the completely change the way hydraulics work in the F-16.

 

Whether it will ever be implemented in DCS or not, I do not know

yeah, big no, that is not the only way...alt gear handle allows stored nitrogen in the alt gear reservoir to introduce nitrogen into the hydraulic lines to "blow down" the gear. I've done many many alt landing gear checks

[Frederf]

I always thought the big white button in the middle of the handle was a release button in order to return the alt gear handle back in. Turns out it's not. It's for bleeding air out of the system. Alt gear operation surely has to be modeled at some point.

[mvsgas]

10 hours ago, sdirmitt said:

yeah, big no, that is not the only way...alt gear handle allows stored nitrogen in the alt gear reservoir to introduce nitrogen into the hydraulic lines to "blow down" the gear. I've done many many alt landing gear checks

 

You write that you have done many alt landing gear checks, but then you also write that the handle introduces nitrogen into the hydraulic lines? If you have done that, you done something very wrong. Pulling the alt gear handle sends pressurize nitrogen to all 3 door actuators and the the NLG retract/extend actuator through its own pneumatic line. That is why there are 3 line on the actuators.

 

 

9 hours ago, Frederf said:

I always thought the big white button in the middle of the handle was a release button in order to return the alt gear handle back in. Turns out it's not. It's for bleeding air out of the system. Alt gear operation surely has to be modeled at some point.

Your not alone, many pilots and some maintainers (weapons loading crews and specialist that work with the avionics) think that also. Pressing the white button resets the landing gear sequence valve in the left MLG wheel well. So if you press the button and pull the handle you are resenting the valve while trying to move it with nitrogen pressure, pushing nitrogen in all the hydraulic lines. I seen that happen several times before and now someone has to bleed the nitrogen out of the B hydraulic system.

[Carbon715]

3 hours ago, mvsgas said:

 

You write that you have done many alt landing gear checks, but then you also write that the handle introduces nitrogen into the hydraulic lines? If you have done that, you done something very wrong. Pulling the alt gear handle sends pressurize nitrogen to all 3 door actuators and the the NLG retract/extend actuator through its own pneumatic line. That is why there are 3 line on the actuators.

 

 

Your not alone, many pilots and some maintainers (weapons loading crews and specialist that work with the avionics) think that also. Pressing the white button resets the landing gear sequence valve in the left MLG wheel well. So if you press the button and pull the handle you are resenting the valve while trying to move it with nitrogen pressure, pushing nitrogen in all the hydraulic lines. I seen that happen several times before and now someone has to bleed the nitrogen out of the B hydraulic system.

I misread the post as I thought you were inferring the only way to drop the gear was via EPU power in a failure situation.

I also should have specified to the door actuators

[Carbon715]

Here is the theory of operation. Main and nose landing gear emergency extension starts by pulling the ALT GEAR handle (fwd or aft) out until fully extended. The ALT GEAR handle motion is mechanically sent by the alternate landing gear control assembly to work the alternate landing gear selector valve. The alternate landing gear selector valve ports pneumatic pressure to the landing gear selector valve emergency spool and to shuttle valves in the NLG retract actuator, on the NLG door actuator, and in both MLG door actuators. These shuttle valves direct the pneumatic pressure to the gear extend side of the actuators. Pneumatic pressure moves the landing gear to shut off hydraulic pressure and interconnect both landing gear extend and landing gear retract hydraulic circuits with hydraulic return. The extend cycle then occurs normally except that the

NLG and door are not sequenced. No pressure is supplied to the downlock actuators since the downlocks are normally set into locked position by mechanical springs mounted on the

actuators. After pushing the ALT GEAR handle fully in, the alternate landing gear selector valve vents the pneumatic pressure from the affected actuators and the landing gear selector valve to the atmosphere. Pressing the ALT GEAR handle reset switch resets the landing gear selector valve emergency spool for normal hydraulic retraction.

[Bouli306]

 

 

On 10/1/2021 at 2:45 PM, mvsgas said:

 

You write that you have done many alt landing gear checks, but then you also write that the handle introduces nitrogen into the hydraulic lines? If you have done that, you done something very wrong. Pulling the alt gear handle sends pressurize nitrogen to all 3 door actuators and the the NLG retract/extend actuator through its own pneumatic line. That is why there are 3 line on the actuators.

Yes, nitrogen is actually introduced in the hydraulic lines via the actuators. That is why you can expect a hydraulic B failure soon after alternate gear extension.  That is why the NWS is not functional after alternate LDG extension.

[mvsgas]

19 hours ago, Bouli306 said:

 

 

Yes, nitrogen is actually introduced in the hydraulic lines via the actuators. That is why you can expect a hydraulic B failure soon after alternate gear extension.  That is why the NWS is not functional after alternate LDG extension.

Go learn about Landing Gear Hydraulic isolation valve, how it works and its relation to the alt gear extension. That will answer why NWS does not work and why no air is introduce to the hydraulics if all alt gear procedures are followed and the system is working as it should. The most common way air is introduced to system B is when people press that reset button at the same time the pull the handle.