Keeping your fuel cap O-rings in great
shape is good fuel cap leak prevention. Just look at what happened to this
really nice B58 Baron from water contamination of the fuel past a poorly
maintained cap and o-ring:
The right engine sputtered to a stop just
after takeoff. Here is the fuel cap center shaft from the above splashed Baron,
you decide!
See the whole article on this B58
engine failure
HERE
Here is a conventional nitrile
rubber Fuel Cap O-Ring (the larger outer one) after a short while in service,
typically a year or less, in my experience:
Below is a picture of my
fluorosilicone fuel cap O-ring taken on 12/13/14 (yeah, that's a cool date) which
has nearly 6 years TIS! You and your A&P decide which you want to use.....
Here is a Bonanza that is
definitely in need of fuel cap o-rings. This Bo owner couldn't get his
fluorosilicone o-rings fast enough
after he saw this on his flight
Why wait for this to happen to
you?
Fluorosilicone Fuel Cap Kits from Gallagher Aviation, LLC.
Shaw Model 431 and 531 Series
Caps
Click the link below to buy ONE O-Ring Kit
for ONE 431 or 531 Fuel Cap.
Add additional Fuel Cap kits when item is
in your Cart
-----------------------------------------------------------------------------------
Shaw Model 416 and 516 Series
Caps
Click the link below to buy ONE O-Ring Kit
for ONE 416 or 516 Fuel Cap.
Add additional Fuel Cap kits when item is
in your Cart
-----------------------------------------------------------------------------------
Gabb Model Caps
Click the link below to buy ONE O-Ring Kit
for ONE Gabb Fuel Cap.
Add additional Fuel Cap kits when item is
in your Cart
-----------------------------------------------------------------------------------
D'Shannon 15 Gallon Screw Type
Cap
Click the link below to buy ONE O-Ring for
ONE D'Shannon Screw Type Fuel Cap.
Add additional Fuel Cap kits when item is
in your Cart
-----------------------------------------------------------------------------------
D'Shannon 15/20 Gallon Flip Top
Type Fuel Cap Kit
Click the link below to buy ONE O-Ring for
ONE D'Shannon Screw Type Fuel Cap.
Add additional Fuel Cap kits when item is
in your Cart
Here is a P35 Bonanza fuel
selector that is
definitely in need of the center shaft o-ring. The owner reported leaks when
selecting the right tank.
This looks like a great
opportunity for a fluorosilicone o-ring (with your A&P's approval of course)!
Why wait for this to happen to
you?
See more on fuel caps at CSOBeech
HERE
See a Shaw 531 Fuel Cap O-Ring
Change Article written by
BeechTalker, David M. HERE
Thanks for the contribution David
There is some confusion about the
big o-ring for the GABB cap as to whether it is a -338 or a -339. The IPC calls
out a -339, however, folks report that the -339 is somewhat loose and pops out
of the slot. The -338 seems like a better fit. Just a watch out that you double
check what's being used in this application!
Here is a pic of a Gabb cap
where the owner reports a good fit using a -338 o-ring
O-Ring Cross Reference
HERE (circa 1995 - use at your own risk)
Listings of my favorite B55 & Other O-Rings
(Check your parts catalog to be sure they will work for
your SN)
Military Nitrile Rubber
O-Rings
- *
There is some confusion
about the big o-ring for the GABB cap as to whether it is a -338 or a -339.
The IPC calls out a -339, however, folks report that the -339 is somewhat
loose and pops out of the slot. The -338 seems like a better fit. Just a
watch out that you double check what's being used in this application!
-
MS29513-010 (4) =
B55 Fuel Selector
Shaft w/Separate Aux Tanks (See Narrative
HERE)
O-Ring
Reference Guide PDF
HERE
Buna-N (Nitrile) O-Rings
Description: Standard Nitrile
is also known as Buna-N. Excellent resistance to petroleum-based oils and
fuels, water and alcohols. Nitrile also has good resistance to acids and
bases, except those with a strong oxidizing effect.
Limitations:
Avoid highly polar solvents (Acetone, MEK,
etc.) and direct exposure to ozone and sunlight.
Chemistry:
Copolymer of butadiene and acrylonitrile. By
varying the acrylonitrile content, elastomers with improved oil/fuel swell
or with improved low-temperature performance can be achieved. Specialty
versions of carboxylated high-acrylonitrile butadiene copolymers (XNBR)
provide improved abrasion resistance. And hydrogenated versions of these
copolymers (HNBR) provide improve chemical and ozone resistance elastomers.
Trade Names:
CHEMIGUM ® , HYCAR ® , PARACRIL ® , PERBUNAN
®
ASTM D1418 Designation:
NBR, XNBR, HNBR
ASTM D2000/SAE J200 Type, Class:
BF, BG, BK, CH
Temperature Range:
–55° to 120°C (–65° to 248°F)
Typical Uses:
Ion Implant, PVD
Compound# |
Color |
Hardness
Shore A |
Tensile
Mpa (Psi) |
Elongation % |
22Hr C/S
@ 100C |
Low Temp |
High Temp |
B1000 |
Black |
70 |
15.0 (2,150) |
400 |
10 |
–40°C(–40°F) |
120°C(248°F) |
Fluorosilicone O-Ring Options*
/3 = 60 Durometer
Available from Genuine Aircraft Hardware (List Price $4.50/each WOW)
/1 = 70 Durometer
Available from O-Rings, Inc.
HERE (List Price $0.50/each)
/3 = 60 Durometer
Available from Genuine Aircraft Hardware (List Price $28.00/each WOW)
/1 = 70 Durometer
Available from O-Rings, Inc.
HERE (List Price $6.96/each)
/1 = 70 Durometer
Available from O-Rings, Inc.
HERE (List
Price $4.25/each)
/1 = 70 Durometer Available from O-Rings, Inc.
HERE (List Price $2.75/each)
/1 = 70 Durometer Available from O-Rings, Inc.
HERE (List Price $8.25/each)
/1 = 70 Durometer Available from O-Rings, Inc.
HERE (List Price $1.00/each)
/1 = 70 Durometer Available from O-Rings, Inc.
HERE (List Price $0.50/each)
/1 = 70 Durometer Available from O-Rings, Inc.
HERE (List Price $0.50/each)
-
M25988/1-010
(4) = B55 Fuel Selector
Shaft w/Separate Aux Tanks
(See Narrative HERE)
/1 = 70 Durometer Available from O-Rings, Inc.
HERE (List Price $0.50/each)
/1 = 70 Durometer Available from O-Rings, Inc.
HERE (List Price $2.50/each)
See a failing Bonanza fuel selector o-ring
HERE
Remember: Failing O-rings in
your fuel selector are a prime source of air entering the fuel supply and
creating all sorts of mysterious runability issues in your engine at possibly
the worst possible times!
*Fluorosilicone o-rings, whether 60
or 70 Durometer, have less tear resistance than the military Nitrile rings being
crossed. They may or may not be appropriate for your particular application.
Notice the tensile strength and elongation spec differences in these two
materials. Be sure your mechanic approves return to service.
O-Ring
Reference Guide PDF
HERE
Baron Fuel System Parts
Catalog Extract
HERE
Here is an image of where
o-rings/seals are in the basic Bonanza fuel selector are located and why they
leak in this area.
Bonanza owner and A&P, Bob B. adds this about the fuel
selector o-rings/seals:
These fittings call for a 'special' o-ring
correctly called a boss seal. It is an MS29512-4 or MS28778-4 ( probably a dash
4 but do not quote me.) The dash number indicates fitting size not the same as
normal o-ring sizing nor is it the same material as the usual/standard o-ring
although it looks similar. When a standard o-ring MS28775 for most usage or
MS29513 for fuel are substituted, they will leak after awhile for no apparent
reason. Or The nut may be a little loose or even too tight creating undesirable
extrusion. In either case, remove the fitting, replace the o-ring with a correct
'seal'.
Remember: Confirm all part numbers with your parts catalog
for your serial number airframe!
Baron Owner & IA, Stuart S.,
pirep on Fluoro Silicone: "Mine are like new and they were installed in 1996."
Fluorosilicone O-Rings
Description:
Combines excellent
low-temperature performance of silicone with improved
chemical resistance. Very good resistance to military and aerospace fuels.
Excellent performance
in oxygen plasma environments.
Limitations:
Avoid polar solvents,
hydro-carbon fluids and phosphate ester brake fluids.
Susceptible to hydrolysis by acids and bases. Limited abrasion resistance.
Chemistry:
Methyl disiloxane
with CF3 groups (Methyl-trifluoropropyl siloxane)
(CH 3 )(CH 2 CH 2 CF 3 ) –SiO.
Trade Names:
SILASTIC LS ® , FSE ®
ASTM D1418 Designation:
FVMQ
ASTM D2000/SAE J200 Type, Class:
FK
Temperature Range:
–60° to 180°C (–76°
to 356°F)
Typical Uses:
Dry Etch, Resist
Stripping
Compound # |
Color |
Hardness
Shore A |
Tensile
Mpa (Psi) |
Elongation % |
70Hr C/S
@ 200C |
Low Temp |
High Temp |
F1006 |
Blue |
40 |
7.6 (1,100) |
410 |
20 |
–60°C (–76°F) |
180°C (356°F) |
F1003 |
Blue |
60 |
|
|
|
|
|
F1001 |
Blue |
70 |
7.5 (1,090) |
230 |
15 |
–60°C (–76°F) |
180°C (356°F) |
F1002 |
Blue |
75 |
|
|
|
|
|
F1004 |
Blue |
80 |
6.8 (990) |
177 |
11 |
–60°C (–76°F) |
180°C (356°F) |
Fluoro Silicone PNs Available at
Genuine
Aircraft Hardware &
O-Rings, Inc.
Pirep 8/20/2012:
Reported to be available from
East Coast Aircraft Supply
in Melbourne, FL
800-330-3945
M25988/1-338 $5.25
M25988/1-010 $.40 ea (min order 10)
No O-rings for this "Old School" Fuel Cap for
very early Bonanza airframes. Rumor has it these puppies are quite pricey!
Here are some pics of the real
"McCoy" NOS early Bonanza fuel caps that a certain someone offered for sale
recently at a phenomenal price of $50! Now this is a very good reason to join
and PARTICIPATE in Beechcraft internet forums....The complete Beech PN is:
35-921526-14
Rumor has it the rubber seal
alone is over $200
|