Service difficulty report · Valve · Cessna R172K

Difficulty date
August 8, 2008
Submitted
August 22, 2008
Operation
General aviation
Aircraft
N9927V
Make and model
Cessna R172K
Aircraft serial
R1722354
Part
Valve
Part number
S18271
Condition
Damaged
Location
Nose Strut
Stage of operation
IN
How discovered
V
Nature of condition
O
Precautionary procedure
K

As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.

What was found

A NEW VALVE WAS ORDERED AND INSTALLED TO CURE A SUSPECTED LEAK IN THE VALVE CORE. THE NEW VALVE ARRIVED WITH A BRIGHT APPEARANCE, EITHER CHROME OR NICKEL PLATED. WITH THE NEW VALVE INSTALLED, THE STRUT LEAK WORSENED. AN EXTERNAL INSP REVEALED THAT THE COSMETIC PLATING WAS FLAKING FROM THE HEX FLATS. THE VALVE WAS REMOVED AND IT WAS FOUND THAT THE PLATING WAS ALSO FLAKING IN THE THREAD-AREA, AND THIS RESULTED IN A LEAK AROUND THE VALVE. THIS VALVE EMPLOYS A NPT THREAD (1/4 INCH PIPE THREAD) AND THE THREADS FORM THE SEAL WHEN INSTALLED. THE REMAINING PLATING WAS EASILY SCRAPED FROM THE THREADS WITH A PICK AND THE VALVE WAS REINSTALLED WITHOUT FURTHER DIFFICULTY. SUBMITTER ADMITS THAT THE PLATING RESULTS IN AN ATTRACTIVE PART, HOWEVER THE MFG MAY WISH TO STOP PLATING THE THREADED AREA. (K)

More about the Cessna R172K