The following information is derived from the FAAs Service Difficulty Reports and Aviation Maintenance Alerts. Click here to view “Airworthiness Directives.”
Virtually any aircraft may be subject to fuel contamination following the discovery that certain filters used in fuel farms and fuel trucks may deteriorate.
Velcon Filters Inc., maker of Aquacon and CDF cartridges, has determined that some of its filters would, under some circumstances, allow some of the gelatinous water-absorbing media to pass with the fuel.
As water is absorbed by the water-absorbing media, similar to whats used in baby diapers, the differential pressure will rise and, when the media is saturated, flow is shut off. However, with low water rates and at low flow rates, less than half of the filters rated flow, the differential pressure may not rise and the media may be extruded through the standard filter media.
A 1998 incident in San Diego led Velcon to revise the filters operating parameters and also to develop an improved model, which was introduced in May 1999. However, in mid-July a Piper Archer that was being defueled in Vero Beach, Fla., was found to contain contaminated fuel.
Velcon will replace any of the affected filters free of charge.
Beech 24, C23, and 19 Series
A technician has reported finding similar structural corrosion defects at the forward attachment point for the fuselage channel at fuselage station 132. At this location, a fresh air duct passes through the channel. In one case, the forward channel attachment point was completely consumed by corrosion. Severe corrosion was also found at other various points on the fuselage where fresh air duct boots came into contact with the fuselage structure.The corrosion may have been caused by water leakage from windows and condensation from the air ducts. In many cases, the insulation was wet, which created an environment conducive to corrosion.
Beech C35 Bonanza
Poor Ruddervator and Aileron Repairs
During a maintenance inspection, the technician noticed scab patches on one aileron and both ruddervators.Further investigation disclosed the scab patches were loose, and there was a considerable amount of corrosion present. The blind fasteners, used to secure the aluminum patches to the ruddervator magnesium skin, worked loose. The aircraft maintenance records did not indicate when these repairs were made or whether any effort was made to balance the flight controls. Also, the ruddervator system had excessively loose bushings and worn rod-ends which produced very sloppy control. The owner decided to ground the aircraft and asked the technician to perform a proper evaluation and repair.The owner had purchased the aircraft 25 flight hours earlier without the benefit of a maintenance inspection or an inspection of the maintenance records. However, the annual inspection was signed off when he purchased the aircraft.Aircraft total time – 6,005 hours.
Beech V35A Bonanza
Defective Oil Temp Sending Unit
While investigating the cause of inaccurate engine oil temperature indications, technicians discovered a defective temperature sending unit on the Continental IO-520B. The maintenance records indicated this was the original sending unit installed when the aircraft was new.The technician ordered and received a replacement sending unit. He conducted a receiving inspection, and discovered the replacement sending units wire stud was loose and could easily be rotated by finger pressure. He rejected the replacement sending unit and contacted the vendor. The vendor checked his stock and rejected four other sending units before finding a sending unit that did not have loose wire studs and threaded studs.
Beech B90 King Air
Faulty Electrical Wiring
After operating the air-conditioning system during a phase inspection, the technician smelled and saw smoke in the cockpit.A wire was smoldering under the center cockpit pedestal at the isolation limiter bus. There are two wires at this location. Except for the emergency bus, these wires provide electrical power to the entire aircraft without circuit protection. While removing the wires for replacement, one wire broke at the starter relay. The wire was severely corroded and the insulation displayed evidence of excessive heat damage. Similar aluminum wires were installed in Models 65-90 and 90-Series King Air aircraft through serial number LJ 440.Part total time – 10,007 hours.
Cessna 172N Skyhawk
On the first flight of the day, the student pilot reported the engine would not idle cutoff. When he shut off the engine using the magneto switch, the propeller ran backwards. The instructor stated the aircraft did not idle properly the previous evening, however he assumed hot weather caused the problem. A technician discovered the carburetors upper and lower body halves had separated approximately 0.125 inch. Evidently, the carburetor overhaul facility technician did not torque the bolts properly before he set each bolts lock-washer tab.Part time since overhaul – 25 hours.
Misaligned Rudder Pedals
This new aircraft had less than 100 hours of total operating time. During the first Phase II inspection, the technician noticed the rudder pedals on both pilot stations were not matching in their alignment.The technician discovered the left stations pedals had its mounting arm on the right pedal drilled incorrectly at the point where it attached to the crossover shaft. At the point where the right stations pedals attached to the crossover shaft, the left pedal was also drilled incorrectly.The technician notified the manufacturer of this misalignment problem. The manufacturer sent parts that were properly drilled.Part total time – 97 hours.
Pilot Seat Support Problem
When the pilots seat back was selected in the full-upright position, it was approximately 3 inches back and toward the reclined position.A technician discovered the seat back support fitting was bent. He noted that this was the second fitting replaced on the same seat. The first fitting was replaced after only 23.6 hours of use. This is the fourth failure of the same part within his fleet of new Cessna aircraft.Part total time – 51 hours.
During flight, the pilot smelled and saw fuel in the cockpit. He made an immediate and uneventful landing.An investigation disclosed the fuel hose connecting the filler neck to the main fuselage tank was not attached. The hose separated from the top of the tank flange and allowed fuel to enter the cockpit. The hose was not long enough to allow for the airframe flexing during operational conditions.
Grumman American AA5B Tiger
Defective Aileron Skin
During an annual inspection and compliance with AD 79-22-04, the technician discovered the left aileron skin was delaminated.The delamination varied from 1 to 4 inches where the leading edge skin was bonded to the rib. It was necessary to remove and replace the aileron.Part total time – 1,675 hours.
Piper PA28-180 Archer
Spar Cap Damage
During an annual inspection, the technician found evidence of fretting at the left and right main landing gear legs where they attach to the wings lower spar cap.The technician also discovered the lower attach bolts were not properly torqued, and the attach point bolt holes were elongated on both the gear legs and the spar caps. This allowed a wearing motion between the gear legs and the spar caps.Part total time – 4,040 hours.
Piper PA32RT-300T Turbo Lance II
While complying with AD 79-26-04 and Piper Aircraft Service Letter 882A, the technician removed the rudder. He noticed the attach bolts to the lower rudder fitting were approximately 40 percent corroded. Water standing in the rudders lower attach tube may have caused the corrosion.Part total time – 2,605 hours.
Teledyne Continental TSIO-520
Improper Cylinder Installation
The FAA has recently become aware of field overhaul shops that are knowingly installing the wrong Continental cylinders on some TSIO-520 engines. At issue are overhaulers who are using cylinders equipped with venturi intake valve seats as interchangeable with those that do not contain venturi seats. While this particular issue is not considered a significant safety concern, the FAA is concerned that field overhaulers would take this type of action contrary to the published information provided by the original equipment manufacturer.Installation of unapproved cylinders can lead to the installation of different valve train component parts and could affect oil consumption, compression, engine cooling, and performance.