I am at the gate. Sometimes I see the OVERWING DOORS light up (but they are closed).

It is an alert for a non perfectly not closed door....I try to reopen and close...but the lights are still on.

 

The QRH says: if pressurization is normal--> continue

if press is not not normal --> plan to land

Obviously it refers to an inflight situation.

But what to do when I am at the gate?...in rw I suppose you have to call maintenance to check it

(btw I took off monitoring the light and it switched off after about a couple of minutes)

 

What to do in these cases (as I imagine that taking off it is not the correct procedure !)

 

Thank you!

 

 

This is quirk of the real Boeing 737 as you may know...

The overwing doors are held shut by 28 volt motorised locks, the locks are there to prevent the doors being opened in situations where that shouldn't be done, i.e. in flight, on take off, landing etc, but since they are emergency doors and could be required to be opened in all kinds of situations the locks disengage when the aircraft is in a position where they might have to be opened in order to evacuate the aeroplane. For example, they get unlocked when the aircraft is stopped, also 30 seconds after there is weight on the wheels after landing, or with the throttles somewhat retarded (to be super-precise, for the benefit of any really pedantic home cockpit builder lol, this occurs when the throttles are pulled back to less than a 53 degree angle, at which point they trip a micro switch in the pedestal related to the locks and the PSEU warning light), the overwing doors also unlock if power to the locking mechanism is lost obviously, since in a forced landing or some such, it's likely the power would be cut to the lock mechanism, which only stays in place when powered.

So there is a related issue with this system on the 737; it is most often caused by either a lack of lubricant on the locks, or by the lubricant which is on the locks getting cold and becoming more viscous, or by excessive de-icing fluid residue getting on the lock mechanism and gunking it up a bit. In any case, this slows the operation of the locking mechanism down and the slow movement of the mechanism is interpreted as a malfunction by the aeroplane's warning systems, which is why seeing that warning about the doors not being locked is not uncommon on the 737, so much so that PMDG chose to model this behavioural quirk in their simulated NG.

So, you might see the PSEU light come on in the PMDG NG for this reason, but you won't see that in a 737 MAX because the MAX doesn't have a PSEU light, it has one with MAINT on it instead lol, which may well light up for this reason. But in either case, MAX or NG, with PSEU or MAINT illuminated for this reason is a non dispatchable fault, i.e. the QRH tells you that you should not take-off in this condition. The warning light can only be extinguished by fixing the fault (i.e. you need to check/service the door mechanism, so it's potentially a back to the gate job if you can't get that light out when taxying). However if you only get the PSEU/MAINT warning light on recall, it is classed as a dispatchable fault, so it is acceptable to go with that, since the warning light will go out when Master Caution is reset.

It's worth noting, for those who are curious about how common this quirk actually is, that the problem is less common on 'newer' NGs and also less likely on the 737 MAX, because Boeing tweaked the mechanism a bit on later NGs and of course that tweak is one the MAX inherited.

Some airlines have a procedure which requires an airline staff member to sit by the affected exits if they have not indicated they are locked prior to departure, to prevent a passenger from opening them, so you could simply pretend you've done that if you like, or as noted, you could 'service' your 737, which should also sort the problem out.

Failing that, you can smack the door with a hammer, oh no, that's what you do on a Land Rover isn't it? 😊

 

Edited August 2, 20187 yr by Chock

What to say....

I have more than understood!

Thank you Alan for your complete answer.

2 hours ago, Marenostrum said:

What to say....

I have more than understood!

Thank you Alan for your complete answer.

In addition to Alan's answer, please have a look at the Intro Manual. We explained this there, along with a bunch of other quirks of the real plane that we have simulated.