What drive belt for Airborne vacuum pump?

[rydfly]

Hi folks, I'm new to this group but have been reading along in many posts for quite some time. I'm in the process of purchasing a '53 170B with a dry vacuum pump installed per STC SA15CE. The logs do not contain the original STC paperwork, and my efforts to search the internet have been mostly unsuccessful thus far.

I'm looking to find out what type of drive belt is specified or recommended for use in this application. Right now, the there is a worn out NAPA "Premium XL" 25-07933 installed. Can anyone tell me what the correct replacement belt should be?

Thanks!

[GAHorn]

The STC No. SA3-664 which covers the belt-driven vacuum pump was issued to Airborne Mfg Co, Elyria OH in 1961. The 170 Assn has copies of this STC and installation paperwork (which I will post in the MX LIbrary.)

The V-belt specified is their PN D-6-3-2, which is a SAE HC-38, 31.3" length.

Hope this helps.

[hilltop170]

While the prop is removed to replace the belt, some of the Super Cub guys will zip-tie a spare belt to the engine behind the drive pulley. Don't know how often the belt fails but is cheap insurance if it fails while you're on a trip or off-airport.

[Brad Brady]

While the prop is removed to replace the belt, some of the Super Cub guys will zip-tie a spare belt to the engine behind the drive pulley. Don't know how often the belt fails but is cheap insurance if it fails while you're on a trip or off-airport.

Richard,
I was going to mention that....we keep an air conditioner belt safety wired behind the prop of the S-2R thrush I fly, When in season were not going to pull the prop just to keep the pilot cool!!!! The down side is if you don't need the belt.....in a few years it's just junk......and never needed.....but still good insurance.......Brad

[48RagwingPilot]

Can anyone tell me how to access the standby vacuum pump STC in the maintenace library? Thx.

[GAHorn]

Can anyone tell me how to access the standby vacuum pump STC in the maintenace library? Thx.

It's not a "standby" system. It's a system which replaces the original venturi system with a belt-driven vacuum pump.
Warning: the belt driven system is no longer supported and uses a special vacuum pump for which it is difficult to obtain parts.
The STC is found in the "Engine Compartment" listings: http://www.cessna170.org/forums/viewtop ... =39&t=6800

[Bruce Fenstermacher]

FYI

We have two areas in what is our maintenance library. The first is categorized under areas of the aircraft and contains documents of information that has been collected for the most part since we have had a forum. The link George posted goes to this part of the library. There is another part of the maintenance library which consists of documents that were sent to the Association over the years in the form of 337s with or without documentation. All the these documents were scanned and made available though lots of them have little value today. There are some diamonds in the ruff in there if you look hard enough though. And there are duplications between both areas of the library.

It was just last week one of our new members was looking for the Airborne vacuum system STC documents and I couldn't find them but I only looked in the older area.

The STC document George linked to is not for the 170B but the 172 and later 100 series aircraft. The 170B had a different STC which probably very similar. I don't know if it uses the same belt.

Now down to the brass tacks of the situation. You need a belt. It is perfectly legal under AC -23-27 (http://www.cessna170.org/forums/viewtop ... =43&t=6737) to take that old belt to NAPA and get one that is the same regardless of the name on the belt. Of course it would be nice to determine the old belt you have is the belt intended to be used by the originator of the STC.

[48RagwingPilot]

Thanks, fellas. What I'm looking for is the vacuum pump STC that applies to the C170. My ulterior motive is documentation permitting installation of an early-model C-172 nose bowl on a C-170, which is what's on the airplane I'm trying to buy. Any ideas?

[GAHorn]

Thanks, fellas. What I'm looking for is the vacuum pump STC that applies to the C170. My ulterior motive is documentation permitting installation of an early-model C-172 nose bowl on a C-170, which is what's on the airplane I'm trying to buy. Any ideas?

Just FYI, When looking for approvals You're likely to need to specify exactly which Part No. nose bowls on exactly which model/serial aircraft in order to get that done. ("early" 172 and "170" probably won't suffice for official approvals.)

I.E.: The late B-models used the same cowl nose PNs ast the 56/57 172/172A. Those are not capable of being replaced upon earlier cowlings without modifying those cowls, air box inlets. etc..

Sorry to say, I suspect you're "pioneering" the approval process for what you are considering to purchase.
That's not to say the airplane you're considering is unairworthy, or not a good airplane. It's only to say
the paperwork is not "clean" and it 'll likely take a little effort with the FSDO to make it so. The inspector who has previously been approving the aircraft for return to service in previous annual inspections should be VERY willing to
clear this up for you...if you know what I mean.

[48RagwingPilot]

Thanks, George. Does the association have the vacuum pump STC that applies to the C-170?

[48RagwingPilot]

FYI, the nose bowl currently on the airplane is P/N 0552010-4 and came from a 1961 or 1962 C172.

[Bruce Fenstermacher]

Thanks, George. Does the association have the vacuum pump STC that applies to the C-170?

That would be STC SA15CE and we don't have it to the best of my knowledge. But then I didn't realize we had the 172 version elsewhere that George linked. A search for SA15CE here at the forum didn't turn anything up.

[48RagwingPilot]

Thanks. I'll let you know how it all works out.