Corrosion And leaks

Upon investigating a loose rudder pedal, the controls were disassembled. We found the shaft had been double-drilled with the holes overlapping. This aircraft is a relatively new aircraft, having been certificated in January 2002. Pilots rudder pedal assembly: p/n 002-524040. Left rudder pedal shaft: p/n 002-524016-5.

Editorial Staff

Tuesday, November 27, 2007 at 12:00 AM ET

Verified

Key Takeaways:

Manufacturing defects (e.g., a double-drilled rudder pedal shaft in a Beech A36) and age-related material degradation (e.g., a brittle hydraulic sight-glass in a Cessna 402C) led to critical component failures.
Corrosion was a significant safety concern, found in a Beech G18 wing spar (due to moisture exposure) and elevator torque tubes across multiple Cessna 172 and 18x series models, prompting inspection recommendations and airworthiness bulletins.
Fuel system integrity was compromised in a Cessna 172 due to a cracked primer line, likely caused by vibration, highlighting the need for secure component attachments.
Several incidents underscore the importance of thorough inspections, even on newer aircraft, and routine maintenance for older aircraft to address issues like material fatigue and corrosion.

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Beech A36

Loose Rudder Pedals

pedal assembly: p/n 002-524040. Left rudder pedal shaft: p/n 002-524016-5.

Part Total Time: 1015.4 hours.

Beech G18

Wing Spar Corrosion

Severe corrosion was found in the l/h spar tube at wing station 90. The probable cause is exposure to moisture over an extended period of time. My recommendation would be to seal and liberally apply linseed oil to the tubes interior. A further recommendation would be performing visual and dye-penetrant inspections of this area at 25 hour intervals up to the first 100 hours. If no fatigue cracks are noted, extend the inspections to every 100 hours-or each year-whichever occurs first.

Part Total Time: 6600.0 hours.

Cessna 402C

Hydraulic Reservoir Sight Glass

The hydraulic reservoir sight-glass on this aircraft is a four-inch piece of tubing located on the firewall in the nose cargo bay and protected by a piece of Plexiglas. The sight-glass leaked, allowing hydraulic fluid down into the nose gear tunnel and in contact with the Janitrol heater, causing smoke in the cockpit.

The operator said the Plexiglas was not damaged, so he thinks the tubing became brittle over the years. He has now decided to include a replacement of the sight-glass hose (p/n 5117007-12) with the aircrafts 1000-hour inspection.

Part Total Time: Unknown.

Cessna 172

Primer Line Fuel Leak

Fuel was spraying from the number three cylinder when priming prior to engine start. A mechanic described the primer line (p/n LW12098-1-116) cracked at the welded tip where it attaches to the cylinder and suggests greater security for these primer lines at more places to minimize vibration.

Part Total Time: Unknown.

Cessna 172, 180, 182, 185, 188 Models

Elevator Torque Tube Corrosion

The Australian Civil Airworthiness Safety Authority (CASA) has issued an airworthiness bulletin (AWB 53-006) recommending inspections for corrosion damage on the elevator torque tubes (p/n 0532001-31) in Cessna model 172 airplanes. This part has been installed on Cessna 172s since the model was introduced in 1956.

CASA reports similar problems with the p/n 0734110-7 torque tubes used on some or all Cessna model 18x-series airplanes. The p/n are 0334106 and 0334206.

Part Total Time: Various