O No

Defective batch of O rings swells up when in contact with avgas


The following information is derived from the FAAs Service Difficulty Reports and Aviation Maintenance Alerts.


The FAA has issued a safety recommendation regarding a batch of O rings manufactured by Parker and distributed by Valtec because the rings may swell excessively when coming into contact with avgas. The problem first came to light after the fuel selector valve on a Cessna 180 was rebuilt and the engine then suffered fuel starvation. The O ring had enlarged to twice its original size. The O rings in question bear a part number of MS29513-112, a package date of 06/01 and a lot number of 60002401. The manufacturer concluded that the lot was made from the wrong material due to a mistake by its material supplier.

Aero Commander 500S Shrike
Hydraulic System Failure

The pilot reported losing all hydraulic system pressure during flight.The technician discovered a hydraulic system pressure line had ruptured, allowing the fluid to leak out. The line was routed in an area where it was not supported for about 16 inches. The pressure line ruptured dues to chafing and vibration.Part total time – 2,994 hours.

Beech C24R Sierra
Landing Gear Failure

The lower section of the nose gear separated from the aircraft during takeoff. The pilot was not aware of the problem until informed by controllers just prior to landing. The gear position indicator lights were normal throughout the flight.The bottom half of the nose gear strut housing had fractured at the collar assembly. Both tow limit stop bolts and a nose steering rod-end were bent and distorted, indicating that the strut failure resulted from the turn limits being exceeded when the airplane was towed on the ground.

Beech F33A Bonanza
Landing Gear Failure

The pilot reported the landing gear would not retract.Technicians determined the Eaton dynamic relay would occasionally stick in the down position. After the dynamic relay was replaced, the gear functioned properly.The FAA Service Difficulty Program data base contains 25 reported failures of the same part number relay, which is used in different applications in different airplanes. Part total time – 244 hours.

Beech 58 Baron
Defective Fuel Indicator

During an inspection, a technician discovered the left wing fuel quantity sight gauge was defective.The float arm of the new gauge was indexed 180 degrees from the original gauge, causing the float arm to contact the wing leading edge. The gauge would not read below 45 gallons. He obtained another new sight gauge that also had an index anomaly.Part total time – 0 hours.

Cessna 172R Skyhawk
Wing Skin Cracks

While conducting other maintenance, a technician noticed several cracks on the trailing edge of the left wing skin inboard of the four rivets used to join the trailing edge stiffener to the upper and lower skins. The cracks ranged from 0.5 to 1 inch in length, and one crack penetrated a rivet hole. An additional crack, approximately 1 inch long, was found in the same area adjacent to a rivet joining the extreme inboard rib to the upper skin.

Cessna 177RG Cardinal
Landing Gear Defect

The pilot reported the gear pump motor continued to run after the gear selector was placed in the down position. Also, the gear-down indicator light did not illuminate.A technician discovered the right main down-lock switch was not being actuated because its support bracket was broken. The broken support bracket rotated in the housing and would not allow the gear to lock down. The support bracket lower pin was sheared, and the support bracket displayed signs of excessive heat at the point where it was welded.

Cessna R182 Skylane
Defective Fuel Pressure Gauge

A technician discovered the fuel pressure indicator was defective.An instrument repair facility returned a replacement fuel pressure gauge that produced only extremely low readings. The technician removed the nipple fitting and discovered that copious amounts of Teflon thread tape had been incorrectly applied to the fitting threads, covering about 75 percent of the fitting opening. Also, small pieces of the tape had broken off and entered the gauge.

Cessna 182S Skylane
Fuel System Defect

While completing the airplanes first 100-hour inspection, a technician discovered the fuel strainer standpipe had been manufactured with only one or two threads machined into the standpipe for engagement and retention of the fuel settling bowl assembly. The threads were inadequate to support the weight of the fuel bowl, especially when subjected to operational vibrations. An Airworthiness Inspector from the local FSDO concurred with the technicians findings, leading Cessna to design a new standpipe. Part total time – 100 hours.

Cessna T210N Centurion
Stabilizer Bracket Discrepancy

During a scheduled inspection, a technician discovered a horizontal stabilizer attachment bracket was severely cracked. He inspected another like aircraft and found a similar defect.Cessna Service Information Letter SE84-17 deals with this subject and authorizes the installation of an improved attachment bracket. It also recommends inspections at 100-hour intervals.Part total time – 2,882 hours.

Lake LA-250 Turbo Seafury
Engine Oil System Defect

While complying with Lycoming service information, a technician discovered a defect in the oil pressure system.Lycoming SB 518-C gives instructions for ensuring the airworthiness of the Vernatherm engine oil bypass valve by checking the valve nut for proper tightness. In this case, the oil bypass valve nut was not only loose, it was missing. It was found in the inboard end of the right side oil cooler hose. Part total time – 616 hours.

Piper PA-28-180 Cherokee
Electrical System Alteration

The owner brought his newly acquired aircraft to a repair facility and reported an electrical overvoltage condition.A technician discovered the voltage regulator had been removed from the system. He speculated someone replaced the original alternator with one incorporating an internal voltage regulator and removed the voltage regulator and overvoltage relay. Subsequently, when the alternator was replaced with a new original alternator, which did not have the internal voltage regulator and overvoltage relay, the installer failed to reinstall these components.

Piper PA-28-201 Arrow
Defective Engine Induction System

During a 100-hour inspection, the technician noticed the alternate air door hinge was bent, allowing unfiltered air into the engine intake system.The submitter recommended that the manufacturer modify this installation by increasing the size of the hinge support and using more and larger rivets.Part total time – 99 hours.

Piper PA-31-350 Chieftain
Landing Gear Retraction Problem

The pilot reported a problem retracting the landing gear after takeoff. A technician discovered the main landing gear lock rod fork bolt was sheared in the shank area. Failure of the gear lock rod fork bolt at the wrong time could prevent the landing gear from locking in the down position.

Piper PA-34-200T Seneca
Electrical System Failure

During an engine operational test, the alternators suddenly dropped offline.The technician discovered the electrical system master switch, located on the cockpit left side panel, contained a broken plastic tab that couples the two halves of the switch together.

Piper PA-44-180 Seminole
Induction System Structural Defects

During a 100-hour inspection, a technician discovered severe cracks in both engine carburetor heat boxes. The right engine airbox was cracked at the hot air inlet where the tube is welded to the box. The left engine airbox was cracked at the cold air inlet. The Service Difficulty Program database contains five additional reports of failure of this part.Part total times – 324 and 199 hours.

Univair 415-C Ercoupe
Defective Nose Wheel Steering

When the aircraft was repositioned after a flight, the nose gear steering system failed.A technician discovered the steering rod was severely bent and the nose gear steering joint ball that attaches the nose gear to the steering rod was broken.A manufacturer-revised steering rod is available. The revised steering rod is structurally more sound.Part total time – 1,950 hours.

Also With This Article
Click here to view “Flap Over Cirrus Flaps.”
Click here to view “ADs issued in June.”


Please enter your comment!
Please enter your name here