.125 psid?????? Help!

[ATADave]

Somewhere, perhaps in a previous life, I remember learning that there exists a limit to which an airplane is allowed to be pressurized on the ground of .125psid. This is to ensure that the cabin doors can be easily opened, but allows for a bit of a reduction in thrust bump (which apparently was not a design concern in the RJ’s).

I cannot find any reference to this in parts 25 or 121. The search engine on the FAA web site is crap. Can anyone with a decent FAR program with a real search engine, or perhaps someone who knows the FAR’s better than I please turn me on to a reference for this?

Thanks in advance,
Dave

 

[RT8VA]

I know on the 737 it is in the Limitations of the flight manual and it is .125 for us.

 

[njcapt]

Yep. It's a limitation on the 737, allowed for the reasons stated above. It relates to a little less than 200 below field elevation.

 

[GIII Instructor]

.125 is a specific aircraft restriction... as you can see it exists on the 737 various aircrafts have various requirements. Bottom line - min. pressurization in the event of a ground egress.

 

[gutshotdraw]

The aircraft I have flown pressurize to a max of .3 PSID. It would be aircraft specific and not a generic certification restriction.

 

[Bigoober]

GV is limited to .3psid. It has to do with the area of the emergency exit from what I have been told.

Supposedly, they figured that a typical female's strength would be able to open the overwing exits with this much psid over the area of the exit. Makes sense to me.

Maybe there is a max pounds that can be applied to the emergency exit. The smaller exits can have a larger psid and vice versa.

 

[AA717driver]

.125 for the 757/767. TC

 

[pianoman]

Somewhere, perhaps in a previous life, I remember learning that there exists a limit to which an airplane is allowed to be pressurized on the ground of .125psid. This is to ensure that the cabin doors can be easily opened, but allows for a bit of a reduction in thrust bump (which apparently was not a design concern in the RJ’s).

Actually the ERJ pressurizes on the takeoff roll to around 300 feet below AFE to ease the bump. The only times I've noticed a bad pressure hit was when a packs off takeoff was performed, for obvious reasons. Not sure about the CRJ.

 

[DashTrash400]

DHC-8 is .5 psid

 

[Falconjet]

.125 for the 727 as well.