Vac pump failure

[triple8s]

I realize the trend is moving towards glass but is anyone using a wet vac pump on their Mooney? They are supposed to be very reliable and long lasting.

 

[peevee]

I had no idea they even existed. Do they really last 2k hours? 

[rbridges]

I didn't know it was an option. 

[chrisk]

I had my vacuum pump fail twice last year.  The first time I put a new coupling in it.  The second time I got a new pump.  Looking up the cost, it was $378 for a new pump.  About an hour to put it in.  I think the wet pumps are closer to $1500, and who knows if it requires a 337?   For me, I have an Aspen as a primary and a standard attitude gyro as a backup, (and a precise flight standby since it was already on the plane).  --I still am amazed a STC was approved for a turbo that uses manifold pressure to work as your vacuum backup.  I really wonder how many folks know they need to reduce the manifold pressure (and power) to make the thing work. 

 

 

Got to love the supplement.

The Mooney 231 is equipped with a turbocharger and when taking off utilizing a power setting of 40 in Hg., the intake manifold is pressurized to provide additional power to the engine. Once the aircraft is at cruise speed and power at 8000 ft to 10,000 ft altitude the power setting is reduced to 27 in. Hg. and the engine intake manifold is pressurized by the turbocharger. The Precise Flight Standby Vacuum System relies on the difference between the outside ambient air pressure and the intake manifold pressure, power settings on a turbocharged engine will have to be reduced to allow proper Standby Vacuum System operation

 

Once a turbocharged aircraft is at altitude, and has a vacuum pump failure, a slow and safe descent to landing, using low power settings, will be necessary to effectively operate the SVS system. In the Mooney 231 you can cruise with 18.5 in. Hg. at 8,000 ft. MSL, which will provide the required vacuum to maintain primary gyro instruments. On final approach you will have the best possible vacuum. The aircraft engine, turbocharged or not, is developing more vacuum than the primary gyro instruments need and the vacuum regulator will keep the system within limits.

[Yooper Rocketman]

1 hour ago, chrisk said:

. Got to love the supplement.

The Mooney 231 is equipped with a turbocharger and when taking off utilizing a power setting of 40 in Hg., the intake manifold is pressurized to provide additional power to the engine. Once the aircraft is at cruise speed and power at 8000 ft to 10,000 ft altitude the power setting is reduced to 27 in. Hg. and the engine intake manifold is pressurized by the turbocharger. The Precise Flight Standby Vacuum System relies on the difference between the outside ambient air pressure and the intake manifold pressure, power settings on a turbocharged engine will have to be reduced to allow proper Standby Vacuum System operation

 

Once a turbocharged aircraft is at altitude, and has a vacuum pump failure, a slow and safe descent to landing, using low power settings, will be necessary to effectively operate the SVS system. In the Mooney 231 you can cruise with 18.5 in. Hg. at 8,000 ft. MSL, which will provide the required vacuum to maintain primary gyro instruments. On final approach you will have the best possible vacuum. The aircraft engine, turbocharged or not, is developing more vacuum than the primary gyro instruments need and the vacuum regulator will keep the system within limits.

Thanks for that info.  Can't say I was aware of that issue!

Tom

[triple8s]

I will be checking into this. It just makes no sense to risk a vac pump failure, wrecking all the instruments over a 1500$ pump, one gyro can cost that. 

http://www.airwolf.com/aw/products/airwolf-wet-vacuum-pumps

 

[carusoam]

That old style precise flight system doesn't work under various conditions.  That is why they invented the electric driven vacuum pump alternative.

Being over tall mountains would leave you pretty nervous if you hadn't been familiar with it's operation.  Having to descend to make it work over mountains that you can't descend into would be hazardous... hitting granite clouds vs losing control in IMC is a tough choice.

Fortunately there are other electronic devices with back-up batteries that you can rely on.  Enough that the old MP driven systems are no longer wanted...

I can test my back-up electric vac system before the engine is ever started.  It would be a challenge to test it once the engine's vac pump is on...

vacuum pumps have a nasty way of failing completely and with low time...

Choose a better planB for this.

Best regards,

-a-

[kortopates]

All of the very few people I knew that installed a wet vacuum pump never got anywhere near 2000 hrs on it. But I am kidding a bit, because they all went back to the dry pumps since they got tired of cleaning up the oil that the wet pump constantly leaked onto the belly. Therein is the con, they are very messy. You may not care but you should be aware. If you can, talk to your mechanic and other local pilots and you may be able to look at a local plane that uses one so you can see one for yourself.


Sent from my iPhone using Tapatalk

[StevenL757]

9 hours ago, triple8s said:

I will be checking into this. It just makes no sense to risk a vac pump failure, wrecking all the instruments over a 1500$ pump, one gyro can cost that. 

http://www.airwolf.com/aw/products/airwolf-wet-vacuum-pumps

 

I removed that exact vacuum pump from my ship a few months ago during avionics upgrade.  A helluva' lot more reliable than dry, it was hooked to the air/oil separator so I didn't have the mess to clean up.

I have less than 278 hours on that pump, which is still in pristine condition along with the check valve that comes with it.  PM me if interested and can get this to you for a very fair price.

-Steve

[kevinw]

I was told a wet pump is also heavier than a dry one reducing useful load a bit. This came from a Bonanza owner who is planning to remove his. Not sure if this is true but I would want to know before installing one.


Sent from my iPhone using Tapatalk

[StevenL757]

A Bonanza owner would say that...  :-)

Useful load for wet vs. dry pump installs is a negligible impact to UL.  My W&B data shows 1.1 pounds,  Small price to pay for a solid aluminum billet pump that outperforms any dry pump on the market.

[jetdriven]

17 hours ago, Yooper Rocketman said:

Thanks for that info.  Can't say I was aware of that issue!

Tom

The placard of max manifold pressure allowable by altitude is required to be installed with a precise flight svs system. 

[jetdriven]

13 hours ago, triple8s said:

I will be checking into this. It just makes no sense to risk a vac pump failure, wrecking all the instruments over a 1500$ pump, one gyro can cost that. 

http://www.airwolf.com/aw/products/airwolf-wet-vacuum-pumps

 

The CV1J4 air filter will prevent vacuum pump problems and dust from ruining the gyros. 

[Piloto]

Keeping the plane level without an ADI/HDG in IMC is not as hard as it may seem if you have practice on a simulator. I use the turn coordinator for roll and the altimeter/VSI for pitch. I have a vertical compass that makes it much easier to maintain heading in turbulence. The altimeter/VSI are more sensitive to pitch changes than the ADI indication. With my G530W I can do an ILS approach as good as before. Using rudder pedals and trim for long term stability free your hands. The only drawback is that I loose auto pilot function.

As turn coordinators age they become very sensitive to turns. Make sure yours match the 2 min turn.

José

[Marauder]

On 11/11/2016 at 7:03 PM, Yooper Rocketman said:

Thanks for that info.  Can't say I was aware of that issue!

Tom

Take a look at these numbers from my Precise Flight flight tests to profile the power settings. This was back in the early 90s when glass backups and electric stand-by vacuum pumps were commonly found in GA planes. When the AD hit it, I removed the system.