Except in Culiacan... then Wendel is in charge

Agreed.

My Citation door seems like a toy compared to the MU2 door. And on the other side of it is FL450. Hmmm. Yet the service history is decently good for the Citation door. But you better believe I check the little green flags every time!

Mike C.

I lost the front right windshield at FL260. Sounded like someone discharged a shotgun next to me. Definitely a lot of shock value, made worse by the fact that the 300kt wind made the remaining fragments vibrate like a reed instrument…sounded like the end. Plane slowed with throttle back pretty fast and the vibration stopped. Then declared and made my descent. I did ultimately decide to reach for my mask because I figured I should, but I was so high on adrenaline that I never felt any light headedness so I never put it on as the plane came down like an anvil. I’ve also tried 20min at FL210 off oxygen in a Cessna 210, felt a little “off” on math and technical challenges presented by my airline pilot brother (who remained on oxygen) but definitely still functional.
At the high 30’s and low 40’s it’s a whole different ball game. Lungs work in reverse. Shock and expanding gas causes exhalation. With the next breath you suck in unoxygenated air into your lungs. Hemoglobin in the blood dumps its oxygen at the lung and with the next heartbeat, the unoxygenated blood hits the brain and it’s “lights out.” That’s why even folks who can hold their breath for a few minutes are toast in seconds at altitude.
But at “most turboprop levels” it seems you have plenty of time. I am a 55yo skier/alpinist who lives at 7600 feet and exercises at 9-11K so that may have some bearing on how I feel in high cabins.

Just throwing this out there...have we considered a new thread called, "Jets with the best environmental systems and supplemental oxygen that can achieve 0.7 mach or better?"

... we could do that, but then the thread drift would lead us to tire ply count, or cabin window sunshades, or maybe rudder trim authority.

And the answer would STILL be Mu2 haha

Minor niggle. About 200 ias…

Still think about my MU2 . It’s an overbuilt tank . Great airplane .

There is a big difference between 200 KIAS at 200 KTAS at sea level and 200 KIAS at 300 KTAS at altitude.

Any material in the air, such as debris, dust, shards, etc, are moving at 300 knots.

Mike C.

There is a big difference between 200 KIAS at 200 KTAS at sea level and 200 KIAS at 300 KTAS at altitude.

Any material in the air, such as debris, dust, shards, etc, are moving at 300 knots.

Mike C.

On one of my earlier Citation trips as a co-pilot, when I closed the door, I was amazed that there was a gap that you could see through along the edge. The door seal fills it, but still... (1980 or so, may have been a I or a II)

This is common, and it was normal on the MU2 to also see through the door crack.

You do not want the door seal rubbing on the frame during opening and closing. That wears it out and can also fold or set it in a bad position so it doesn't inflate properly.

Once air pressure is applied, the seal then inflates and makes pressure on the frame to form the seal.

On my door for the Citation V (which may not be true on earlier models and not true for the MU2), there is a secondary door seal.

The secondary door seal serves two purposes. First, when the plane is parked on the ramp, it seals the door against water ingress by being in contact with the frame. Or at least, that is the intention since it sometimes isn't achieved in practice. Second, should the primary door seal after you have been pressurized, then cabin pressure will keep the secondary seal in contact with the door frame and provides a backup seal. That's the curved part with the ribs.

The primary seal pushed the secondary seal into position, so you have to at least had the primary seal work initially to have the secondary seal do its job. If you get no primary seal, usually the secondary seal isn't helping either.

More than you want to know about Citation secondary seals:

[youtube]https://youtu.be/k15ZwcaSOkg[/youtube]

The gap between the seals and the door frame is controlled by applying Bondo to the frame. This is crude and one of the worst design features of the Citation. My Bondo has cracks in it and finding someone skilled in repairing or replacing it has been challenging. I have made small repairs to keep it airworthy for now, but a proper replacement it likely to be needed at some point. Textron service center wanted $10K to do it and I wasn't entirely confident they outcome would be awesome at that price. I sense I will be doing that someday myself, but perhaps someone reading this can suggest a shop for this work. Anyone?

Mike C.

Mike

Interesting parallel here to the Epic. Some Epic LTs used bondo as filler and show cracking in the paint anywhere and everywhere it’s applied. The door area usually shows a lot of cracks.

The solution is to use minimal filler and change the material to “micro” rather than bondo. It tolerates temp changes and expansion/contraction better. Not sure it’s an approved alternate application for Citations

I have no experience with it and that’s all I’ve heard

How thick is the body filler? Anything over 1/4" will crack over time. You could try some flexible body filler when you redo it, maybe that will keep it from cracking.