I totally agree that vac pumps suck (figuratively, especially when they fail to suck literally). Definitely the least reliable thing on the airplane. Still, the physical evidence does not support the argument that they failed in this case.
you can fly on the DG and altimeter without too much skill.
INstead he tried to fly, acccording to his radio reports, on the backup AI. The problem with that is the AI is way over here and the rest of your scan is in front of you. He could probably have done it if he had ever practiced it. I bet when he practiced partial panel, he practiced DG, altimeter, even whiskey compass. I bet the instructor or safety pilot didn't let him use the backup AI. But when he was the only pilot on the flight deck, he couldn't resist trying.
IMC w/partial panel is a bad time to break in new procedures.
Hillarys Gate Cult:
I thought most planes have a back up indicator that isn't powered by pumps.
Some do, some don't. It isn't (or shouldn't be) a death sentence to lose this thing, but it is an emergency and you will be working harder. But... very important. The pumps didn't fail (or the DG would have been indicating wrong at impact too... this is a gyrocompass that is powered by the same vacuum system, and it was pointing right). What failed was the indicator itself.
Squawk 8888:
unless there was a compelling reason (such as low fuel) to make that approach he should have flown to some alternate airport
He was at altitude when he lost control of the plane. He didn't get to the approach phase.
USNBandit :
Depending on when he realized his primary failed he might have already been screwed up when he transitioned to the other instrument.
Good catch, and like you say moving your head around when you have no visual horizon reference is a recipe for disorientation.
the news reported right after the accident that the FAA had active TDs out on that type of aircraft for the instruments
There were two service bulletins that might be relevant (not mandatory AD's). One was definitely in Carnahan's possession (found in wreck) and witnesses said he was complying with it. Other one, nobody knows if he received it, but it was sent to same address as the first.
Dan(9698) :
This airplane is a twin and so would have had vacuum pumps on both engines.
It did, and also, the system is designed in such a way that one pump alone is enough. The second just provides redundancy. If one fails, the vacuum system automatically seals it out of the circuit.
snopercod:
I'm going all electric on my Lancair....Ever read Bob Nuckoll's Aeroelectric Connection?
Good idea, wave of the future, dual redundant buses, no vacuum instruments. ISTR the SR22 I flew was set up like that (factory exp). Never heard of Bob, I'll check him out on your recommendation.
the pilot was attempting to use the right-side AI indicates that he was unable or unwilling to use the needle-ball-airspeed method on the gages right in front of him.
I think he thought it would have been easier to do the off-side AI than needle-ball-airspeed. That AI indicated exact attitude at impact, which wasn't badly banked, or even severely nose down. It had just been nose-down long enough to break 300kt (which needle-ball-airspeed would have caught for sure). What's the VNE in one of those things? Immaterial if you do what NTSB calls "uncontrolled collision with trees and terrain." I don't think I'd be comfortable anywhere near 300kt in a Cessna twin.
expatpatagain:
It would be interesting to know if the two AI's each had separate vacuum pumps or if both ran off the same pump, with the other as backup for the first pump.
Ahhh... read the NTSB report. Not trying to be a smart-ass, but the vacuum system of the 335 is fairly involved (depending; for some of you guys with multiple type ratings, and especially who flew 40s and 50s equipment, it's trivial) and there are a couple of pages on the system there. Basically both pumps pull a vacuum on one shared vacuum manifold. The air they pull in is blown out into the deicing system. Each pump has a pressure relief valve to keep the vacuum from being too much. Each pump has a check valve at the manifold, so if it fails it's automatically cut off (so the surviving pump doesn't have to pull vacuum all the way out to the failed one). All vacuum operated instruments attach to that manifold. ONE PUMP CAN RUN EVERYTHING FINE. The POH says no action is necessary for a failed pump; just squawk it on landing.
?Dan again:
I see you explained the check valves. Cool. After reading the comments about his log book, it is obvious he was over his head.
For the record, it seems he had been flying regularly but was not keeping his log up. (Giving him the benefit of the doubt, maybe he was transitioning to a computer based logbook). I had a T210 (single) and flew almost 1000 hours combined IFR and night. They are almost the same.
My dad had one, I still miss it. He tells me buy my own. LOL.
JETDRVR:... not being taught correctly in todays fine institutions of flight instruction....
I don't know that any one thing did him in. A bunch of small things, but to me, going against training and trying something new (flying on the offside AI) is no good.
On a personal note , my wifes Grandfather just passed into eternity and we do miss him so. He was and is a Mans Man a Hunter Fisher Gardener and just in general a lover of life and of all human beings.
May God have mercy on his soul, sir, and may he be waiting for us all with advice on the best sporting locations in Paradise.
FreedomFlynnie:
Is there a ping list for flying threads?
I'm not sure. I thought bootless started one about three years ago! So I pinged her, too. If there isn't one, there should be. Who knows how?
d.o.l.
Criminal Number 18F
bootless is very busy right now organizing SMX-gig, so I took the liberty of starting an aviation-related ping list in her stead. Let me know if you want on or off.