The bulletin
Text extracted from the PDF.
SPECIAL
AIRWORTHINESS
INFORMATION
BULLETIN Aircraft Certification Service Washington, DC U.S. Department of Transportation Federal Aviation Administration No. CE-00-34 September 12, 2000 We post SAIBs on the internet at "av-info.faa.gov" This is information only. Recommendations are not mandatory.
Introduction This Special Airworthiness Information Bulletin (SAIB) provides safety information associated with Supplemental Type Certificate (STC) SA1361SO installed on Cessna Model 421C aircraft. This SAIB advises and alerts you, an owner or operator, repair station, mechanic holding Inspection Authorization (IA), and Principal Maintenance Inspectors (PMI) in the Flight Standards District Offices (FSDO) of service difficulties associated with the STC.
Background STC SA1361SO is currently issued to Canadian Turbo Prop, Inc. of Aldergrove, British Columbia, Canada.
This STC replaces the two Continental GTSIO-520 engines on the Cessna Model 421C with two Pratt and Whitney PT6A-135 engines. During the maintenance of a converted Model 421C, the mechanics found the high pressure fuel line that goes to the fuel flow divider on the right engine chafed. The service difficulty report estimates that approximately 75% of the fuel line wall thickness had been chafed away. The stainless steel rod which is part of the actuator assembly for the anti-icing door caused chafing. The left engine also showed a lesser degree of chafing. The chafing problem is common to both engines. It appears that excessive engine movement due to worn engine isolator mounts caused some chafing.
Recommendations The FAA recommends inspections in the area of the high pressure fuel line to the flow divider at the next annual inspection of aircraft with installed STC SA1361SO. If chafing is found, the chafed fuel line should be replaced with a new fuel line bent to provide greater clearance, and you should also replace the engine isolator mounts. If chafing is not found, we recommend that you repeat this inspection at each annual inspection.
For further information, contact Mike Pasion, Seattle Aircraft Certification Office, 1601 Lind Ave. SW, Renton, WA 98055; phone (425) 227-2594; fax (425) 227-1181; e-mail: mike.pasion@faa.gov.