Vacuum Pump Failure Accident Report (Bonanza)
Moderators: GAHorn, Karl Towle, Bruce Fenstermacher
Vacuum Pump Failure Accident Report (Bonanza)
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
Vacuum Pumps
I know a pilot examiner in Merced, CA who was giving a private pilot test in a CE 172 when he noticed the vacuum guage go to zero. Moments later there was smoke from the engine compartment followed by a total engine failure. Fortunately, he landed safely in inhospitable terrain. Seems the vacuum pump drive shaft seized up or something like that and took out accessory drive system. I guess you dont have to be imc for a vacuum pump to become a problem.
Another thing this examiner told me after this accident that I think is intersting: he will never give a test in an airplane without shoulder harnesses. Says they saved his life.
Another thing this examiner told me after this accident that I think is intersting: he will never give a test in an airplane without shoulder harnesses. Says they saved his life.
Re: Vacuum Pumps
I thought the drive shafts on the pumps were plastic so they would break easily and not damage the rest of the accessory section.voorheesh wrote:Seems the vacuum pump drive shaft seized up or something like that and took out accessory drive system.
Karl
'53 170B N3158B SN:25400
ASW-20BL
'53 170B N3158B SN:25400
ASW-20BL
Loss of gyro incidents can be greatly reduced by replacing
the electro mechanical units now in use.
The airlines are paying $90,000 irus. used in the airbus A320
Now I see that a portable unit with more capabilities.
is on the market for $2500. The technology is available to
relegate this class of accidents to history.
Here is a link to a low cost portable unit that can be as
a secondary reference source.
http://www.mc.com/vistanav/products/index.cfm
the electro mechanical units now in use.
The airlines are paying $90,000 irus. used in the airbus A320
Now I see that a portable unit with more capabilities.
is on the market for $2500. The technology is available to
relegate this class of accidents to history.
Here is a link to a low cost portable unit that can be as
a secondary reference source.
http://www.mc.com/vistanav/products/index.cfm
Mike
N 9545A
N 9545A
For the examiners crash, it was'nt the vaccum pump's shaft that seized but rather the oil pumps shaft which drives the vaccum pump. See the accident report here: http://ntsb.gov/ntsb/brief2.asp?ev_id=2 ... 062&akey=1
George I've been thinking about the way I actually fly when I find myself not being able to see outside the fuselage. I'm not saying it's the right way, because no one taught me this. But it might make for thoughtful discussion.
How dependent are we on our vacuum instruments? This is the Attitude Indicator and Heading Indicator?
When I go VFRIFR, my eyes immediately go to the Airspeed Indicator and don't stray very far there after. 1st thought - Don't Stall After I'm comfortable, holding a steady airspeed, and take a relaxing breath, I'll look at the Altitude Indicator to verify that I'm not climbing or descending. That's all there is to not falling out of the sky!
Next is just to find direction, which is easily done with the compass.
Of course the GPS shows airspeed, altitude, going up / down, and direction.
Am I forgetting something or mixing my instruments up?
How the heck does one fall out of the sky if the vacuum instruments go dead?
How dependent are we on our vacuum instruments? This is the Attitude Indicator and Heading Indicator?
When I go VFRIFR, my eyes immediately go to the Airspeed Indicator and don't stray very far there after. 1st thought - Don't Stall After I'm comfortable, holding a steady airspeed, and take a relaxing breath, I'll look at the Altitude Indicator to verify that I'm not climbing or descending. That's all there is to not falling out of the sky!
Next is just to find direction, which is easily done with the compass.
Of course the GPS shows airspeed, altitude, going up / down, and direction.
Am I forgetting something or mixing my instruments up?
How the heck does one fall out of the sky if the vacuum instruments go dead?
Last edited by AR Dave on Sun Nov 19, 2006 1:34 am, edited 1 time in total.
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flat country pilot
- Posts: 230
- Joined: Thu Mar 16, 2006 1:46 pm
Hi Dave,AR Dave wrote:George I've been thinking about the way I actually fly when I find myself not being able to see outside the fuselage. I'm not saying it's the right way, because no one taught me this. But it might make for thoughtful discussion.
How dependent are we on our vacuum instruments? This is the Attitude Indicator and Heading Indicator?
When I go VFRIFR, my eyes immediately go to the Airspeed Indicator and don't stray very far there after. 1st thought - Don't Stall After I'm comfortable, holding a steady airspeed, and take a relaxing breath, I'll look at the Altitude Indicator to verify that I'm not climbing or descending. That's all there is to not falling out of the sky!
What does one really need the Attitude Indicator for?
Next is just to find direction, which is easily done with the compass.
Of course the GPS shows airspeed, altitude, going up / down, and direction.
Am I forgetting something or mixing my instruments up?
How the heck does one fall out of the sky if the vacuum instruments go dead?
Well, one thing I know is that if once a VFR pilot enters the cloud and they stare at the airspeed indicator long enough, when they do think about looking at the other instruments, the other instruments might be spinning so fast as to not make much sense. ( please don't ask how I know this
)Great Topic!
Joe
51 C170A
Grand Prairie, TX
51 C170A
Grand Prairie, TX
Dave, while you may be thinking that airspeed (AS) information is all you are obtaining from that quick glance at the instrument,... you are undoubtedly also assimilating a lot of other information at the same time. For example, you are also already aware of any increasing/decreasing sounds of wind, increasing/decreasing sounds of rpm, etc., in your rapid assessment of aircraft attitude. In other words, you are not simply relying on a fixed indication of say, 92 mph, as assurance that all is well with your airplane. You also have the background info from your ears and butt that your airplane is not decending/climbing/upside-down/etc. In other words, you are actually assimilating LOTS of inputs in order for you to determine what you so desperately want to know.... attitude ... and subsequently, trend.
The airspeed indicator is actually a secondary instrument. It reflects the result of aircraft attitude and power...in a delayed, not an instantaneous fashion.
The primary attitude instrument is the artificial horizon (referred in some airplanes as the ADI, AH, or VG (Vertical Gyro). Imagine, for a moment, you have closed your eyes for a while to inspect the back-sides of your eyelids....(dozed off).... The FIRST instrument to check is the artificial horizon. THEN the airspeed, altimeter/vertical speed, and compass are checked as a follow up action, to determine that they support/confirm the information presented by the AH...and to confirm that the attitude is contributing to the desired trend.
This is why in recent decades the so-called "basic T" has been promoted in panel designs. It presents the primary instrument directly in front of the pilot. In "the old days" the AH was considered an unreliable instrument because it was relatively complex (compared to other instruments) and had narrow pitch/bank limits to the gyro gimbals (meaning it could be "tumbled" and remain so for a protracted period.)
The primary IFR instruments were: the T&B (needle/ball) and the airspeed. The T&B provided turn information (which, if the aircraft were in coordinated flight...i.e., the ball was in the center)...thereby reflecting bank information. And the airspeed reflected pitch information (assuming a constant-power setting exists, and in conjuction with the altimeter and vertical speed indicator/VSI.)
That's a lot of assumptions and a lot of instrument scanning and interpretation that is required in order to determine aircraft attitude and path. The artificial horizon condenses that pitch and bank information into one instrument. The other instruments then take on secondary status for the purpose of confirming that the AH info is valid.
An excersize that can be used to reinforce this, that can be repeatedly demonstrated,... is to subject a pilot to an unusual attitude while his eyes are deliberately closed. For example, you close your eyes while I rev the engine, toss the airplane about, and then say to you, "OK, Dave! It's all yours!"
If the instrument you first check is the airspeed, and it indicates 92... so what? Will it remain there? Not if I've given you the airplane pointed 30-degrees up and the power is at idle. Also, not if I've given you the airplane pointed 30-degrees down and the engine is at full-throttle. (And if you are in a 60-degree bank while pointed 30-degrees down and your first reaction is to pull that nose up to level flight...you'll be placing the airplane at risk of pulling into a deadly tightening-spiral with risk of exceeding the wing/tail design-loads.)
How to properly react? FIRST determine BANK ....and roll the wings level. THEN determine pitch and bring the nose up to the horizon. How? You can't do that with the airspeed. You can with the artificial horizon.
And the opposite manuever... the 30-degrees up? FIRST get the nose down to the horizon. (Some pilots like to deliberately bank the aircraft, if it's not already, in order to relieve the wings of the lift-vector, and thereby allow the nose to fall quite naturally and avoid negative G's.)
In either case, if nose up, ADD power. If nose down, REDUCE power. But the FIRST thing to do is determine PITCH and BANK ...and the primary instrument for that is the artificial horizon...with secondary confirmation info coming from airspeed/T&B/ALT.
The airspeed indicator is actually a secondary instrument. It reflects the result of aircraft attitude and power...in a delayed, not an instantaneous fashion.
The primary attitude instrument is the artificial horizon (referred in some airplanes as the ADI, AH, or VG (Vertical Gyro). Imagine, for a moment, you have closed your eyes for a while to inspect the back-sides of your eyelids....(dozed off).... The FIRST instrument to check is the artificial horizon. THEN the airspeed, altimeter/vertical speed, and compass are checked as a follow up action, to determine that they support/confirm the information presented by the AH...and to confirm that the attitude is contributing to the desired trend.
This is why in recent decades the so-called "basic T" has been promoted in panel designs. It presents the primary instrument directly in front of the pilot. In "the old days" the AH was considered an unreliable instrument because it was relatively complex (compared to other instruments) and had narrow pitch/bank limits to the gyro gimbals (meaning it could be "tumbled" and remain so for a protracted period.)
The primary IFR instruments were: the T&B (needle/ball) and the airspeed. The T&B provided turn information (which, if the aircraft were in coordinated flight...i.e., the ball was in the center)...thereby reflecting bank information. And the airspeed reflected pitch information (assuming a constant-power setting exists, and in conjuction with the altimeter and vertical speed indicator/VSI.)
That's a lot of assumptions and a lot of instrument scanning and interpretation that is required in order to determine aircraft attitude and path. The artificial horizon condenses that pitch and bank information into one instrument. The other instruments then take on secondary status for the purpose of confirming that the AH info is valid.
An excersize that can be used to reinforce this, that can be repeatedly demonstrated,... is to subject a pilot to an unusual attitude while his eyes are deliberately closed. For example, you close your eyes while I rev the engine, toss the airplane about, and then say to you, "OK, Dave! It's all yours!"
If the instrument you first check is the airspeed, and it indicates 92... so what? Will it remain there? Not if I've given you the airplane pointed 30-degrees up and the power is at idle. Also, not if I've given you the airplane pointed 30-degrees down and the engine is at full-throttle. (And if you are in a 60-degree bank while pointed 30-degrees down and your first reaction is to pull that nose up to level flight...you'll be placing the airplane at risk of pulling into a deadly tightening-spiral with risk of exceeding the wing/tail design-loads.)
How to properly react? FIRST determine BANK ....and roll the wings level. THEN determine pitch and bring the nose up to the horizon. How? You can't do that with the airspeed. You can with the artificial horizon.
And the opposite manuever... the 30-degrees up? FIRST get the nose down to the horizon. (Some pilots like to deliberately bank the aircraft, if it's not already, in order to relieve the wings of the lift-vector, and thereby allow the nose to fall quite naturally and avoid negative G's.)
In either case, if nose up, ADD power. If nose down, REDUCE power. But the FIRST thing to do is determine PITCH and BANK ...and the primary instrument for that is the artificial horizon...with secondary confirmation info coming from airspeed/T&B/ALT.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
-
Bruce Fenstermacher
- Posts: 10327
- Joined: Tue Apr 23, 2002 11:24 am
Man you said a mouth full George. And very nicely I might add.
I'd been thinking how to respond to Dave and wanted to give you time to flex your fingers on the keyboard.
I'd been thinking how to respond to Dave and wanted to give you time to flex your fingers on the keyboard.
CAUTION - My forum posts may be worth what you paid for them!
Bruce Fenstermacher, Past President, TIC170A
Email: brucefenster at gmail.com
Bruce Fenstermacher, Past President, TIC170A
Email: brucefenster at gmail.com
I'll also echo a good job by George for his explanation of how to....
One thing I'll add is you have no idea how fast things happen when a VFR pilot gets disorientated in the clouds....it's fast....
Many years ago as a new VFR pilot I got in the soup and to this day I owe my future to a damn good controller at PDX who took me under his wing once I confessed that I was in the clouds and in a heep of trouble....and because of this incident I've since gotten my instrument rating.
Good topic...
One thing I'll add is you have no idea how fast things happen when a VFR pilot gets disorientated in the clouds....it's fast....
Many years ago as a new VFR pilot I got in the soup and to this day I owe my future to a damn good controller at PDX who took me under his wing once I confessed that I was in the clouds and in a heep of trouble....and because of this incident I've since gotten my instrument rating.
Good topic...
Bill
'52 170B
'52 170B