Leaking fuel caps

[Pinecone]

Is installing the O-rings "preventive maintenance" so can be signed off by me?

[OSUAV8TER]

5 minutes ago, Pinecone said:

Is installing the O-rings "preventive maintenance" so can be signed off by me?

It is not an identified item in the preventative maintenance section of the  FAR. Additionally, going to fluorosilicone to me, is a minor alteration, requiring a logbook entry by an A&P mechanic. 

[PT20J]

The o-rings should be lubricated periodically. The Mooney SB cited above calls for Tri-Flow on the shaft to lubricate the small o-ring (this is a good idea on the gascolator and fuel selector shafts also) and Tri-Flow or Vaseline on the large o-ring. EZ Turn also works well on the small o-ring when you install it. I found EZ Turn too sticky and use Vaseline for the large o-ring. Vaseline doesn't last as long, however. I have blue o-rings installed 6 years ago that look like new.

Skip

[N201MKTurbo]

14 minutes ago, PT20J said:

The o-rings should be lubricated periodically. The Mooney SB cited above calls for Tri-Flow on the shaft to lubricate the small o-ring (this is a good idea on the gascolator and fuel selector shafts also) and Tri-Flow or Vaseline on the large o-ring. EZ Turn also works well on the small o-ring when you install it. I found EZ Turn too sticky and use Vaseline for the large o-ring. Vaseline doesn't last as long, however. I have blue o-rings installed 6 years ago that look like new.

Skip

If you are away from home and they get sticky, a drop of oil from your dipstick works wonders.

[EricJ]

2 hours ago, Pinecone said:

Is installing the O-rings "preventive maintenance" so can be signed off by me?

No, but it's the sort of thing that's pretty easy and could be supervised by your A&P/IA and signed off.

[Hank]

4 hours ago, OSUAV8TER said:

I carry the blue flourosilicone o-ring fuel cap kits and most Mooney aircraft need my Shaw 431/531 fluorosilicone o-ring kit. They are $14 a kit and I have them in stock. They come with the large and small o-ring, along with a new cotter key. I have had the original fluorosilicone o-rings on my fuel caps of my Bonanza for 7 years with no signs of deterioration and I have left the aircraft out in heavy rain with no fuel contamination. 

You can order them off my website at https://www.gallagheraviationllc.com/products.html

Also consider the Marsh Brothers GF polymer washer kits. Your current fuel cap washer is a stainless steal ring that wears down your plunger making it challenging to close properly and more difficult to open and close. These things are a little pricey but they are miracle works. Most Mooneys need the -2 kit that comes with 2 washers.

 

I installed these blue o-ring sets at annual, while the IA watched. Then he and I together tweaked closing the first cap and I did the second one under supervision. Quick, easy and painless.

My plane was parked outside under a strong enough storm that I received an audible warning on my phone; the sky was black to the ground. Not a drop of water was found in either tank. The joys of traveling away from home! But the beach was very nice.

[RobertGary1]

Every year you have to inspect them. Once you have the cap taken apart might as well change the rings. They’re very inexpensive. Been outside more than 20 years haven’t gotten any water in my tanks yet. 

[PT20J]

Yhe SB only requires visual inspection of the large o-ring, adjusting tension if required and a pressure test.

[cliffy]

If you do change the small one be sure to use a brass tool to remove it from the hole bore.

Do not use a sharp pointed pick (like the pink handled ones from HF) to try and pry it out

If you do you will scratch the groove it sits in and it won't seal 

A piece of 1/8 brass welding rod hammered to a spoon like end works well and won't ruin the cap bore.