The concern sheetOCR
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Airworthiness FAA Concern Sheet Date: October 15, 2007 Raymond Johnston Make, Model, Series, Serial No.:
Aerospace Engineer Cessna, 525B, -0001 through -0013 Wichita ACO - ACE-119W Avionics & Electrical Systems 1801 Airport Rd. Reason for Airworthiness Concern: Wiring unprotected against Wichita KS 67209 shorts between aircraft DC power and ground.
316-946-4197 raymond.johnston@faa.gov FAA Description of Airworthiness Concern (Who, What, Where, When, How? Attachments: RA and appropriate data) Cessna reported an incident that occurred on August 27, 2007 in which there were numerous in-flight failures of various aircraft systems caused by a direct 28Vde short circuit to ground that is at least partially attributed to incorporation of a Service Bulletin (Cessna SB525B-24-02, Rev -). On the incident aircraft (525B-0008, N51HF), wiring was found burned in the right, left, and emergency electrical power distribution panel sections (J-box) located behind the aft pressure bulkhead.
Additionally the voltmeter circuit breaker and left power limiter circuit breaker were tripped. Failure or opening of power bus limiters in conjunction with incorporation of SB525B-24-02, Rev - may result in loss of numerous aircraft systems and burned aircraft wiring. The instructions and wiring diagrams in SB Rev- 28Vde is incorrectly connected to an annunciator panel where there should be a ground, and terminal 2 of circuit breaker HZ050 is left with no wiring connected, resulting in a direct short. Airplanes incorporating this revision of the Service Bulletin should not be operated, unless they have incorporated a corrective Cessna EO (FAA Approved Engineering Order), or those that have incorporated Cessna Service Bulletin SB525B- 24-02, Rev 1 or later approved revision.
Request for Information (Proposed Alternate Inspection/Repair Procedures, Cost Impact, Etc. Note: Any comments or replies to the FAA need to be as specific as possible. Please provide specific examples to illustrate your comments/concerns.): Cessna is revising Service Bulletin SB525B-24-02 to correct wiring connection callouts and diagrams. The FAA is considering the issuance of an Airworthiness Directive in conjunction with the revised Cessna Service Bulletin. Only information requested is whether or not owners have incorporated SB525B-24-02, Rev -.
This Airworthiness Concern Sheet (ACS) is intended as a means for FAA Aviation Safety Engineers to coordinate airworthiness concerns with aircrafi owner/operators through associations and type clubs. At this time, the FAA has not made a determination on what type of corrective action (if any) should be taken. The resolution of this airworthiness concern could involve an AD action or an SAIB, or the FAA could determine that no action is needed at this time. The FAA's final determination will depend in part on the information received in response to this ACS.
The FAA endorses dissemination of this technical information to all manufacturers and requests association and type clubs comments.
Attachments: *SDR(s) *A/IDS_ *SL(s)[X *SAIB| *FAASR/*NTSBSR *AD *AMOC[*RAL Notification: FAA [X | *AOPA | *EAA Type Club | *TC Holder < Other: GAMA Response Requested 11/06/07: Emergency (10 days) Alert (30 days) X Information (90 days) - (Space Bar Adds "X" to Check Boxes) *Service Difficulty Reports (SDRs); Accident/Incident Da stem (A/IDS); Service Letter (SL): Special Airworthiness Information Bulletin (SAIB):
Federal Aviation Administration (FAA)/National Transportation Safety Board (NTSB) Safety Recommendation (FAASR/NTSBSR); Airworthiness Directive (AD); Alternate Method of Compliance (AMOC); Risk Assessment (RA); Aircraft Owners & Pilots Association (AOPA);
Experimental Aircraft Association (EAA); Type Certificate (TC) Revised T/24702