More Navion Files!

Here are more files of potentially useful Navion information. Again, these documents, and my verbiage, may not be (and probably aren't)
the latest versions. Use at your own risk!

Each of these files unzips into about 10 pdf files. Each pdf is one page in the L-17 (Navion) repair manual (87 pages).

Back when E series engines and their military 470 counterparts were popular, folks started to run out of accessory drive pads. The well dressed Navion had a hydraulic pump, fuel pump, vacuum pump, and perhaps a propellor governor; each of these needed an accessory drive. The engine only had two (left and right). Lo and behold, Hartzell, from the goodness of their Hartz, produced the ubiquitous "T" drive (or "Y" drive, as it is referred to in the Ryan and North American drawings).
The "T" drive allows you to run two accessories from one drive pad; they are no longer manufactured and command a king's ransom when you do find one. That said, their internals ARE still manufactured, consisting of standard bearings, gears, and seals. However, a first time installation comes with a few simple caveats. First, these drives are NOT interchangeable! According to the Type Certificate, only the Continental E-185 engine may use the C-192 drive! And according to the Hartzell drawings, only the E-205, E-225, and 470 engines may use the C-137 drives! Furthermore, these drives obtain their lubricating oil from the engine. You must remove the seal (Continental Part Number 25102) from the accessory drive pad you are planning to use, and in the case of the C-137 drive, do some minor machining on the accessory pad adapter. This allows the oil flowing through the drive to return to the engine sump. ALSO, two of the accessory case studs will have to be replaced with longer versions (Continental Part Number 402129P003 or otherwise listed) to accommodate the thick "T" drive. Still with me? There's one more thing. There are FIVE versions of these drives; you must use the correct version depending on engine, accessory pad, drive rotation, and, in the case of prop governors, the governor you're driving. My E-185 engine driving a wet vacuum pump and hydraulic pump on the right accessory pad uses a C-192-2 "T" drive. So... here are the Hartzell drawings:

Sorry, these are large blueprints. There is no good way to post these in a way that is printable, but they are viewable.

If you really want to go crazy with these things, here are the Hartzell documents for adding a C-137 "T" drive to your left side accessory pad, along with the details of the Hartzell A-1 Propeller governor installation. The first document is the verbiage, and the second unzips into four jpg drawings. By the way, the Hartzell A-1B and A-1F models are interchangeable for the diaphragm controlled props (90-110 PSI oil pressure relief valve), as are the A-1C and A-1E for the piston controlled props (215-235 PSI oil pressure relief valve). However, the E and F models are no longer supported, but the B and C models are very easily convertible from one to the other.

are wonderful things. They let you scramble for approach plates at the last minute without worrying (too much) that the plane is going to roll over on her back.
5186K has a Century I autopilot, originally manufactured by Mitchell, then Edo-Aire, and now Century Flight Systems. This is is a neat unit, as it replaces the turn coordinator, hence relieving the ever present panel real-estate problem. It does a good job of wing leveling, a fair job of course and Nav tracking, and a poor job of course interception. Anyway, it's STC'd for the Navion, which is the only reason it rates space here, and components are a dime -a-dozen. However, Century will charge you an arm and a leg for a copy of the STC (SA3077SW-D), and even more for the installation kit (AK533), which consists of a cable and a couple of brackets. Now for the interesting part. The turn coordinator that drives this set-up contains exactly four (4) major moving parts- the gyro bearings; and Century lists them as being Barden bearings. Well, Barden doesn't even have engineering records for the rotor bearings anymore! But take heart! After years of digging and research, they turn out to be...Timken bearings. Yup! The same excellent folks that make the big tapered roller honkers in our landing gear!

!!! WARNING !!!
Only a certified instrument repair station can work on aircraft instruments, including autopilots and autopilot components. The following material is for general interest ONLY, and is NOT meant as a do-it-yourself guide to autopilot repair, modification, or installation! I take NO RESPONSIBILITY WHATEVER for anything you may do with this information!

The Barden rotor bearing SFR2-5SSTA5 is a Timken S518FMCHH7P58LO2 (stainless steel, flanged, 2/16" bore, 5/16" OD, shielded both sides, 0.5 to 0.8 mil radial play, one piece snap-in phenolic spacer, with light oil lubrication). And the Barden gimbal bearing SFR2-5SSW3VL is basically the same bearing with a loosely crimped, two piece steel spacer and a very low starting torque specification (1000 mg-mm to be precise). This puppy cross references to a Timken S518FRHH7P24LO2Q10.

Here's the link to Century Autopilots
http://www.centuryflight.com/

And here's the link to the best bearing site on the web
http://www.timken.com/

If you want to deal with Barden Bearings, go here
http://www.bardenbearings.com/

The Century servo is pretty foolproof, but it contains a ferociously powerful Globe planetary gear motor which you can replace to the tune of $700 or so. Or you can replace the parts that wear out, the bearings and brushes (for about $25 each). The bearing part number is 15D022A016, and the brushes are 40D553. If you insist on going whole hog, the motor part number is 318A196-6. God only knows what the planetary gear drive part number is. I don't, and I don't want to. Internally, it looks like it probably costs more than the entire airplane. You can buy gyros and servos for a song from Preferred Air Parts (go back a page). The gyro (turn coordinator) part number is 52D75-3 without a nav tracking circuit, and 52D75-4 with. Serial numbers ending with E or F are the latest versions. The servo for the Navion is part number 1C363-1-553R. Century can convert one servo to another (usually just a capstan change and slip clutch torque adjustment). And yes, they'll charge you another arm and another leg.

Deal with Globe at
http://www.globe-motors.com/home.html

Or order the parts from their distributor, Avnet
http://www.avnet.com/

And here's the AutoCad file for the servo mounting bracket
Servo Bracket (dwg file; 0.033 MB)

If you'd like to see the "guts" of a Century I , Steve Williams has an excellent series of photos posted at
Century I Disassembled
Please note the conditions under which these photos may be redistributed!

EXTERIOR HARDWARE

Of course, the original Navion didn't come with stainless steel fasteners, and if you've still got the originals they may be a bit hard to remove at this point. When you do, here's an Excel spreadsheet with the stainless steel replacement part numbers.
CAUTION: The large access panels under the wings which cover the gear mechanism are fastened with STRUCTURAL screws. Don't accept any other for these critical fasteners!

Stainless Hardware (xls file; 0.018 MB)

Note also that some of the original hardware has no easily obtainable stainless replacement. In general, the difference amounts to sixteenths of an inch in length, or truss heads instead of pan or washer heads. The hardware in this spreadsheet works on my 1950 Navion A. Double check clearances before you assume it will work on yours!

OWNER BUILT PARTS

For years there have been rumors that an owner can make, or have others make, parts for his "orphaned aircraft". Well, it's not a rumor. If you have the material and the drawings, the FAA says go ahead! Here's the letter from the Federal Aviation Administration's Donald P. Byrne with the official word!

Owner Built Parts (doc file; 0.030 MB)

HYDRAULICS and FILTERS and HOSES

That big filter element in the hydraulic fluid reservoir rarely gets changed, which is unfortunate because it's so easy to do. It's a standard industrial hydraulic filter, and always has been. Use a NAPA Gold 1071 or 1080, an AC Delco PF-316, or a FRAM C-134PL. The FRAM filter has its own gaskets, so you don't need the big "O" rings normally found at the top and bottom of the filter. The AN902-8 gaskets referred to in the Parts Manual are more than obsolete.They were superceded by AN6290, then MS28778, and are now SAE-AS28778 gaskets. It boils down to an "O" ring 0.644 inches I.D. by 0.087 inches thick.
All of the other seals in the canopy model are listed in this Excel file, both in their original "AN6227" format, and the MS28775 replacement:
Navion_seals (xls file; 0.016 MB)
This Excel file list all of the hydraulic hoses and fittings for the canopy model
Navion_Hoses (xls file; 0.017 MB)

GREASE

So you religiously follow the 55 year old maintenance manual for your pride and joy, being careful to use only the finest AN-15-G grease. Right? Yeah, Right. Don't despair, that Mil-Spec has been obsolete since Hannibal went sleigh riding behind elephants. But if you laboriously dig through a stack of antique Mil-Specs, you'll find that AN-15-G is......
AeroShell Grease #6. Use it everywhere that AN-15-G is specified, which is basically the entire airplane. Of course the Harthell prop used to get only Lubriplate 630-AA, but Hartzell has recently specified AeroShell #6 for all of their propellers. This is a good thing, as the Lubriplate was pretty runny stuff, and tended to spatter the windshield with oil on hot days. Some owners specify AeroShell #5, which has even less tendency to run than #6, but if used the prop must be placarded against operation below -40 degrees Fahrenheit. Technically, the A-38 bearing requires ExxonMobile Andok 260 grease which is no longer manufactured. Fortunately, Nye Lubricants has a Mil-Spec replacement known as Rheolube 374A. This stuff is quite expensive, but you only need an ounce.

AeroShell's Website
Lubriplate's Website
Nye Lubricant's Website

All of these site's have on-line stores where you can either buy or sample these greases, although you can generally find them for less if you shop around. I used to buy the Lubriplate 630-AA in 10 ounce tubes, and repack it into a miniature grease gun just for the prop.

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