Chafing And Cracks

Tuesday, September 26, 2006 at 12:00 AM ET

Verified

Key Takeaways:

Multiple aircraft models reported critical component failures, including chafing fuel lines in a Beech 58 Baron, cracked horizontal stabilizers in a Cessna 152, cracked brake cylinder assemblies in a Cessna 170B, and repeatedly cracked exhaust risers in a Rockwell 114.
Several incidents involved components installed via Supplemental Type Certificates (STCs), such as brake assemblies and turbo exhaust systems, or issues related to older aircraft designs lacking later reinforcements.
The reports emphasize the importance of regular and specific inspections, recommending a one-time inspection for potential fuel line chafing and incorporating brake cylinder checks into preflight routines to prevent serious safety hazards.

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

Beech (Raytheon) Model 58 Baron

Chafing Fuel Line

While retracting and extending the landing gear for adjustment of a drooping inboard main wheel door, abnormal noise and vibration (was noted at mid-cycle). Further investigation found the r/h main landing gear retract rod assembly chafing on the wheel wells fuel crossfeed tubes (p/ns 002-920000-49 and 002-920000-51).

Visual inspection of these fuel tubes found the chafing to be negligible. The tubes were repositioned and secured as required for clearance with the retract rod during retraction/extension operations.

A one-time inspection of this area is recommended (to prevent) chafing and subsequent fuel leakage.

Part Total Time: 187.4 hours.

Cessna 152

Cracked Horizontal Stabilizer Spar

On a routine 100-hour inspection, a crack was found on the horizontal stabilizers front apex, specifically the lower angle (p/n 0432001-44) and the reinforcement plate (p/n 0432001-44).

The lower skin rivet seam was also found fretted and loose. Upon removal and disassembly additional defects…were discovered, including cracked skin (p/n 0432001-55) and a cracked spar (p/n 0432001-56).

This is an earlier serial-numbered aircraft lacking the reinforcement angle (p/n 0432007-3) as installed on later aircraft.

This aircraft also had been converted to a tailwheel configuration per STC SA 175GL.

Part Total Time: 8207.6 hours.

Cessna 170B

Cracked Brake Cylinder Assemblies

The aircraft was equipped with brake assemblies installed in accordance with STC SA13GL. In both brake assemblies (p/n 30-63A), the cylinders (p/n 091-02200) were found to be cracked across and parallel to the anchor bolt hole (bolt p/n 069-00400).

This is the second aircraft found with cracks in these cylinder assemblies.

This brake area is readily accessible and should be part of the preflight inspection. The cracks are easily seen when you are looking for them.

Part Total Time: (unknown).

Rockwell 114

Cracked STC Exhaust Risers

A submitter describes finding multiple holes and cracks in the exhaust risers of the aircrafts turbo system, installed under STC SA00356DE. These exhaust units were deemed unserviceable after only 207.8 hours since new. An added note indicates the new, replacement risers also cracked after just 140.0 hours.

Part Total Time: 207.8 hours.