NTSB · Safety Recommendation
Safety Recommendation A-67-012
Recommendation
RECOMMENDS THAT SUCH AN INSPECTION BE REQUIRED OF THIS MODEL. THE SAME OR POSSIBLY INCREASED SUSCEPTIBILITY OF CERTAIN OTHER AIRPLANES TO THE SAME TYPE OF DETERIORATION MERITS YOUR ADDITIONAL CONSIDERATION OF SIMILAR INSPECTION REQUIREMENTS. AIRWORTHINESS DIRECTIVE 59-22-3 DID PROVIDE FOR THE DETECTION OF THIS TYPE DETERIORATION ON MOONEY M-18 MODELS BUT WAS A ONE-TIME INSPECTION WITH COMPLIANCE REQUIRED NO LATER THAN DECEMBER 15, 1959. THE RENEWAL OF THIS AD, WITH COMPLIANCE REQUIRED ANNUALLY, SHOULD AID INTHE DETECTION OF SUCH HAZARDS.
SPECIAL CONSIDERATION MAY BE REQUIRED EVEN THEN, HOWEVER, TO INSURE THAT AGING, PROCESSING OR OTHER CHARACTERISTICS RELATED TO THE BONDING AGENT HAVE NOT PRECLUDED A MEANINGFUL VISUAL INSPECTION.
Safety Issue and Context
THE WOOD AND GLUE JOINT CONSTRUCTION FOUND IN A NUMBER OF GENERAL AVIATION AIRPLANES OPERATING TODAY WARRANTS OUR CONTINUED CONCERN FOR THE EARLY AND EFFECTIVE DETECTION OF STRUCTURAL DETERIORATION. THE LATTER, OF COURSE, CAN EFFECTIVELY RESULT IN DEGRADATION OF AN AIRCRAFT'S ORIGINAL FACTOR OF SAFETY. THIS DETERIORATION, IN SOME INSTANCES, IS CHARACTERIZED BY WOOD ROT; IN OTHERS BY AN INEFFECTIVE GLUE-JOINT.
IN ANY CASE, THE GENERAL SUSCEPTIBILITY OF THESE AIRPLANES TO THE ADVERSE EFFECTS OF CLIMATIC VARIABLES AND THE UNPREDICTABLE EFFECTS OF VARIATIONS IN WORKMANSHIP, MATERIALS, AND PROCESSES MERIT AN INCREASINGLY VIGILANT AND RECURRENT MAINTENANCE PROGRAM TO INSURE THEIR CONTINUED AIRWORTHINESS.
Response History
April 18, 1967 · Recipient Response · FAA
THE MATTER OF WOOD DETERIORATION ON THESE MOONEY AIRCRAFT HAS RECEIVED CONTINUING ATTENTION BY THIS AGENCY. THE MOST RECENT CAUTIONARY ALERT TO OWNERS AND OPERATORS OF THE MODELS M-18 AND M-20 APPEARED AS A MAINTENANCE NOTE IN THE GENERAL AVIATION INSPECTION AIDS SUMMARY, ADVISORY CIRCULAR NUMBER 20-7B, DATED AUGUST 1965. OUR SERVICE RECORDS AT THIS TIME ON THE MOONEY M-18 DO NOT BEAR OUT THE NEED FOR SPECIAL REPETITIVE INSPECTIONS SUCH AS ARE SPECIFIED IN AD 66-2-4 FOR MODEL M-20 AIRCRAFT.
IN THE INTERVAL SINCE WE INITIATED PERIODIC ALERTS TO OWNERS AND OPERATORS ON THE NEED FOR THOROUGH EXAMINATIONS OF SPECIFIC AREAS OF THE WOOD STRUCTURE OF MOONEY AIRCRAFT, NO REPORTS HAVE BEEN RECEIVED ON THE MODEL M-18 THAT WOULD JUSTIFY THE NEED FOR SPECIAL INSPECTIONS ON AIRCRAFT THAT UNDERGO ANNUAL INSPECTION. WE SHARE THE CONCERN FOR THE EFFECTIVE DETECTION OF STRUCTURAL DETERIORATION OF WOOD AND GLUE JOINTS ON GENERAL AVIATION AIRCRAFT. HOWEVER, IT IS BELIEVED THAT THE PROBLEM IS UNDER SATISFACTORY CONTROL IF THE REQUIRED ANNUAL AIRWORTHINESS INSPECTION IS CONDUCTED AND COGNIZANCE IS TAKEN OF THE MAINTENANCE ALERTS ISSUED ON THE SUBJECT.
IN ADDITION, OUR MALFUNCTION AND DEFECTS REPORTING PROGRAM HAS STIMULATED MANUFACTURERS OF WOOD AIRCRAFT TO ISSUE DETAILED SERVICE INFORMATION TO OWNERS AND OPERATORS ON THE DETECTION OF WOOD AND GLUE DETERIORATION.