The concern sheet
Text extracted from the PDF.
Revised 1/24/02 Airworthiness Concern Sheet
Full Name Andrew McAnaul Title Aerospace Engineer Organization ASW-150 Department Address 10100 Reunion Place, Ste. 650 City State ZIP San Antonio, TX 78216 Telephone Number 210-308-3365 E-mail andrew.mcanaul@faa.gov Make, Model, Series, Serial No.: Allied Ag-Cat Productions, Inc.
Models: G-164, G-164A, G-164B, G-164C, G-164D All Serial Numbers Reason for Airworthiness Concern:
Rudder Tubular Spar Corrosion Date: 5/21/2008 FAA Description of Airworthiness Concern (Who, What, Where, When, How? Attachments: RA and appropriate data)
The FAA issued AD 78-08-09 to visually inspect and corrosion treat rudder tubular main spars on certain serial number Ag-Cat Model G- 164, G-164A and G-164B airplanes. The AD specifically requires a one-time modification, inspection and corrosion protection of the internal cavity of the rudder main tubular spar in accordance with Grumman American Service Bulletin No. 61 dated June 6, 1977, and additional repetitive inspections of the exterior of the spar every 300 hours thereafter.
Since that time numerous later serial number Ag-Cat airplanes unaffected by the AD, including G-164C and G-164D models, have been modified with “tall” rudders to gain additional surface area for higher horsepower applications, or received replacement aftermarket rudders, all of which may have been manufactured in the same manner and configuration as original earlier rudders. On March 22, 2008 a model G-164B, serial number 586B, crashed on take-off when the rudder tubular spar failed where the main tube is welded to the lower fitting. This later airplane’s serial number is not included in the existing AD 78-08-09, and it had a replacement “tall” rudder installed. The initial investigation revealed the lower fitting separated from the rudder main spar tube due to severe internal corrosion, a result of moisture being trapped in the lower portion of the internal cavity formed by the rudder tube and lower fitting. This portion of the rudder spar is also covered with fabric and paint, which makes this area difficult to inspect.
The FAA requests any information from aircraft owners, operators, or repair facilities regarding any inspections performed on Ag-Cat rudders where corrosion or in-service damage was found. Please include any information about the airplane model and serial number, location and size of any damage found, and what action was taken to repair or return the airplane to service. You may also propose Alternate Inspection/Repair Procedures, comment on any potential 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).
A risk assessment accomplished in accordance with the Small Airplane Directorate Airworthiness Concern Process guide for the potential condition is attached. The resolution of this airworthiness concern could involve AD action or SAIB, or the FAA could determine that no further 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 owners/operators and requests association and type club comments.
Attachments: *SDR(s) *A/IDS *SL(s) *SAIB *FAASR/*NTSBSR *AD *AMOC *RA
Notification: FAA *AOPA *EAA Type Club *TC Holder Other: NAAA
Response Requested __/__/__: Emergency (10 days) Alert (30 days) Information (90 days) (Space Bar Adds “X” to Check Boxes) *Service Difficulty Reports (SDRs); Accident/Incident Data System (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)