Limitations

[FastEddieB]

I wanted to spin this off, since the other thread got pretty far afield from its original topic.

 

Right now, what elicited this was the Limitation in the CT POH of a minimum crew weight.

 

"Limitations" are found in Section 2 of the POH for any modern aircraft. They do carry the force of law, as far as I know. Get caught violating one (other than in an emergency, and only to the extent needed to meet that emergency) and you may end up doing some 'splainin' to the FAA and maybe even lose your license for a while.

 

Discussing the reasons behind limitations for the sake of furthering knowledge and understanding is a good thing.

 

Discussing the reasons behind limitations so that you know which ones you can disregard is not so good.

 

I'm sure we all have seen Limitations that left us scratching our heads. Maybe this thread would be a good place to air and discuss them.

 

I don't think I've found any weird Limitations in my Sky Arrow POH, but let me mention two that came up in the Cirrus world.

 

1) As delivered, my Cirrus SR22 POH had this Limitation:

 

"Maximum Operating Altitude ..................................... 17,000 Feet MSL"

 

This was weird. The rules change at 18,000 feet for Part 23, so why give a number 1,000' less? Performance was not an issue - other planes certified under earlier rules with the same IO550 Continental have much higher "Service Ceilings", and the Cirrus was still climbing decently at those altitudes.

 

On an eastbound VFR flight that meant the highest usable altitude was 15,500'. There are certainly situations where 17,500' would clear clouds or ice but 15,500' would not. In any case, the original certification paperwork did show 17,500' as the Maximum Operating Altitude. Some of us carried that in the plane to show that the POH number was most likely a typo. Sure enough, it turned out it WAS a typo, and was changed in a revision.

 

2) Check out this Limitation on Portable Oxygen Systems (which I think is still in effect)

 

(click to enlarge)

 

 

Note that if you wanted to carry supplemental oxygen, it had to be a specific brand and model and the tank had to be in the front passenger seat!

 

I guess the reason for that one was to be able to see the gauge on the tank without going through contortions. And the John Denver accident does show that contortions can have safety implications. Still, I suspect many Cirrus pilots still hung the tank on the back of the seat, as is done in virtually every other plane I know of.

 

Again, maybe this can be a thread of "weird" Limitations and speculation as to how they may have come about,