Gallagher Aviation Fuel Cap O-Rings

Gallagher Aviation’s fluorosilicone fuel cap kits offer unparalleled durability for a variety of types of fuel caps. Flurosilicone fuel cap o-rings help keep fuel in and keep water out compared to the less superior rubber nitrate o-rings. Rubber nitrate o-rings often need replaced and quickly dry rot and deteriorate over time. These fuel caps are found on many Beech, Piper, Mooney, and some Cessna type aircraft. Each kit comes equipped with the appropriate o-rings and cotter pins for replacing large and small o-rings on your fuel caps. One kit equips one fuel cap. Fluorosilicone O-rings can withstand a broader range (-100 to 350 degrees Fahrenheit) whereas Buna-N (nitrate) has a lower temperature range (-70 to 180 degree Fahrenheit). O-ring manufacturers provide Certificates of Conformance and are ISO17025 certified.

Why You Need This Kit

Mooney Service Bulletin Number S.B. M20-229A requires rubber nitrate fuel cap o-rings to be changed every 100 hours/annual inspection after initial compliance. A Beechcraft Baron 58 crashed in Calhoun Kentucky and the NTSB cited as a Probable Cause that “..both failed to detect the long-term water contamination of the fuel system and the deteriorated outer O-rings on both fuel caps…Exposure to weather, fuel fumes, fuel, and possibly other elements have a deteriorating effect on O’ring packings and seals.”

Installation and Continued Airworthiness

Kits provide standard aircraft parts acceptable under 14 CFR §21.9 for a FAA certificated mechanic to install two military specification fluorosilicone type o-rings on Shaw 531, 431, 416, or Gabb style fuel caps. Kits are eligible for installation by a licensed mechanic as a minor alteration under 14 CFR §1.1 and §21.93(a) as it has “no appreciable effect on the weight, balance, structural strength, reliability, operational characteristics, or other characteristics affecting the airworthiness” of the aircraft. No STC, Form 337 submittal or FSDO field approval is required per FAA Order 8900.1 Figure 4-67. A §43.9 airframe logbook entry is sufficient to document this alteration and return the aircraft to service. S.B. M20-229A recommends keeping “the O-ring seal around the cap assembly should be kept clean and free from dirt or grit that might cause abrasive action on scal or mating flange. The shaft running through the center of the cap housing, that actuated the rotating lock plate should be lubricated occasionally with Tri-Flow, or equivalent, to prevent binding while opening or closing the cap assembly. This should also lubricate the O-ring that seals this shaft.