Why is it when I test my reverse thruster at the gate they work but when I land they do not? any idea?

Usually when the main gear touches down first, the reverser and (armed spoilers) do not function until the nose gear is rolling. This is what I have experienced over the past few years anyway. It also may be a failure that is active.

What is a active failure and how do I make it not active?

You probably dont need to worry about that, if you dont know.

 

Anyway sometime the engines dont go all the way to idle on touchdown, try pressing F1 after touching nosewheel down, then press and hold F2.

 

 

Also, these are thrust reversers, not reverse thrusters.

Indeed.

The engines need few seconds to spool down from flight idle to ground idle...

Some red herrings in this thread.The nosewheel does not need to be on the ground, nor should the engines need to spool down to idle to engage reverse thrust. In fact being at flight idle is part of the design of the system, the higher rpm means the engine gets to full reverse faster.

 

The key things are the main wheels being on ground and the thrust levers in the reverse range.

 

Pressing F1 first before pressing and holding F2 can speed up reverser deployment if the thrust levers were still above idle at touchdown.

 

FWIW it is 10ft RA so even mains dont need to be OG IRL, but we are discussing a sim here. Stuff happens in there.

I tried F2 will work at gate but will not work on trying to slow on landing. spoilers armed, AT off auto brakes armed Autopilot off  all wheels down push F2.Still will not work.once stoped they work ????

The PMDG 737NGX adds thrust automatically when the gear is deployed (from up to down)  in flight. It will be above "normal" idle thrust even when your hardware throttle is fully back/closed. Flightsim X sees this as being "above idle thrust".

 

My suggestion is, after you touch down, press and hold F1 for about 1 second, then press F2 to deploy the reversers.

 

If you find the reversers deploy for only a short time then close, you may need to add a null zone to your throttle in calibration so that "fully closed" throttle position on your hardware throttle (or joystick with paddle-throttle control) isn't just a 0.1mm band of area but a slightly larger band (so that when you pull the throttle closed, loosening the throttle forward a hair-width doesn't open the throttle to 0.01% thrust and cancel your reverse thrust).

 

Pressing F1 at touch down (rather than just pulling the hardware throttle to idle) helps ensure Flightsim X sees your throttles at idle thrust (which were pushed forwards slightly without you seeing or doing anything due to the way PMDG NGX simulates the raised N1% level of 'idle thrust' with the gear down in flight.

 

Action:

On Landing (main gear on ground): Press F1 (not F2) for 1 second (a good full "count 1-and-a-release")

Then > Press F2 for reverse thrust activation

This problem keeps rearing its head on the forum, but unfortunately hasn't elicited an official response by PMDG on the issue yet (as far as I'm aware). Leaving aside jittery hardware throttles and poorly calibrated null zones, it does look like a bit of an NGX bug to me. Spamming the F1 key just prior to touchdown and/or using FSUIPC seem to be the generally accepted workarounds, although your mileage will undoubtedly vary.

i have managed to work round this by using fsuipc and then programming one of my saitek levers to press F1to reset to gnd idle and then continue to reverse with the rest of the lever movement

 

1st set the area when you want to press F1

 

 

2nd setup the remaining reverser settings

 

OK thanks I will Try the F1 on landing then theF2. Will advise

PMDG modeled the NGX engine EEC control correctly in that for the standard aircraft configuration engine idle-thrust delay time on touchdown is retained for 5 seconds before reverting to Ground Minimum Idle. In the REAL aircraft you could just open the reverse sleeve during this period, with FSX you cannot do that until the idle hits minimum and then you continue into reverse mode. I find that by the time this happens autobrake has you nearly slowed to the reverse minimum N1.

 

Selecting use of the Short Field package reduces the engine idle-thrust delay time to 2 seconds.

 

Also worth noting that many airports only permit IDLE reverse in normal situations anyway.

 

FCOM 2 - 7.20.7

Ok did a short flight and did F1 after killing autoT  then did F2 and it worked fine. That must be what I have to do all the time.Thanks so much for all the input.

PMDG modeled the NGX engine EEC control correctly in that for the standard aircraft configuration engine idle-thrust delay time on touchdown is retained for 5 seconds before reverting to Ground Minimum Idle. In the REAL aircraft you could just open the reverse sleeve during this period, with FSX you cannot do that until the idle hits minimum and then you continue into reverse mode. I find that by the time this happens autobrake has you nearly slowed to the reverse minimum N1.

 

Selecting use of the Short Field package reduces the engine idle-thrust delay time to 2 seconds.

 

Also worth noting that many airports only permit IDLE reverse in normal situations anyway.

 

FCOM 2 - 7.20.7

FSX does not require the engine to be at ground idle, FSX doesn't even know about flight and ground idle.  All it looks at is the thrust lever position.  Anyway I'm sure PMDG modelled approach idle properly in their custom engine model, not by fiddling with FSX thrust lever position.

 

I've just tried this in my NGX and can confirm that reverse can be deployed as soon as the aircraft touches down.  Any additional delay is entirely to do with how users have their hardware throttles set up.  I use a simple throttle control on a Sidewinder joystick, no FSUIPC calibration, and have no such problems.

 

FWIW it is 10ft RA so even mains dont need to be OG IRL, but we are discussing a sim here. Stuff happens in there.

Yes I was aware of that, but I was trying to keep things simple.  The aircraft has to be in ground mode, and as you say the on ground logic includes a <10 ft radio altitude signal.