Originally Posted by MX727

If you are going to fly depressurized, you probably want to get down to 25K max. Of course, I'm probably thinking of the USAF rules and the mighty Tweet.

Originally Posted by FliFast

if you totally depressurize the airplane, will the cockpit smoke evac handle (the vacuum cleaner port) be ineffective to clear cockpit smoke using differential pressure.

Anyone have some -400 knowledge to share..thanks.

Inquiring minds want to know,
FF

Originally Posted by Huck

Seems like you'd still have venturi suction.

But would that just pull smoke into the cockpit?

Originally Posted by Jetjok

As for the T-37, unless they changed it after I graduated from UPT, way back in 1974, it was, and still is an unpressurized aircraft, with a USAF imposed altitude limit of 25,000 feet.

Originally Posted by FliFast

Let me see how little I know about the -400....

Fire Main Deck

Main Deck Cargo Fire Arm Switch..Armed

This shuts down Tu-pac (two packs). Correct me if I'm wrong, but it shuts off pack 2&3, and pack 1 goes to high flow to increase fresh air to the cockpit. Correct ?

If so, what happens if you have a pack#1 trip on climbout...what does the system do then ???


Secondly, equipment cooling is now in a closed loop..whatever that means.

So now the smoke/override valve opens to evacuate smoke using reverse flow differential-AND- the Flight Deck Equiptment Cooling Source Valve opens to the E&E compartment to use "conditioned air" to cool the screens and the radio racks.

Let me ask someone that knows about the -400. If you shed packs 2&3 and pack 1 has tripped is there any "conditioned air" to cool the screens and the radio racks ? If the radio racks get hot can they malfunction ? Thirdly, if you have a pack #1 trip, is this procedure still valid ?


Then:
Cargo Fire Depress/Disch Switch...push
This opens the outflow valves to depressurize the airplane to a 25,000 foot target altitude. The question again, if you have shed two packs and a third is inop, will the aircraft be able to modulate the outflow valves to achieve a 25,000 foot cabin altitude ? Secondly, if you totally depressurize the airplane, will the cockpit smoke evac handle (the vacuum cleaner port) be ineffective to clear cockpit smoke using differential pressure.

Anyone have some -400 knowledge to share..thanks.

Inquiring minds want to know,
FF

Originally Posted by Jetjok

Apparently the author of the original WSJ article, Mr. Andy Pasztor, doesn't understand how the atmosphere works, relative to where all the oxygen is hiding out. I believe he simply made a mistake in his article. As for the T-37, unless they changed it after I graduated from UPT, way back in 1974, it was, and still is an unpressurized aircraft, with a USAF imposed altitude limit of 25,000 feet. It was a good rule, because there have been pilots, over the years, who took their unpressurized aircraft above 25K, only to turn up at the front end of a crash site. A fellow from Huntington Beach, California, by the name of Ken Rand, did that very thing back in the mid-70's with his experimental Rand KR-2. Seems he took it up into the 30's, only to have his oxygen system ice up. He passed out and the plane flew itself into the ground, and I stopped building my KR-2, right then and there.

JJ

Originally Posted by BoeingJetDriver

JJ -


....I am ****ed off that he "heard" from three sources that one of the pilots of Flight 6 left the flight deck. So much for the GCAA and NTSB putting a muzzle on the respective parties.
My two cents.

BJD