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SPECIAL AIRWORTHINESSINFORMATION BULLETIN
Aircraft Certification ServiceWashington, DC
U.S. Departmentof Transportation
Federal AviationAdministration
CE-05-71July 15, 2005
http://www.faa.gov/aircraft/safety/alerts/
This is information only. Recommendations aren?t mandatory.
Introduction
This Special Airworthiness Information Bulletin (SAIB) updates information previously provided in SAIB CE-05-21, issued December 15, 2004, and provides additional safety information to you, owners and operators of airplanes equipped with Alaskan Bushwheel Tundra Tires, part numbers (P/N) 26126, 29136, and 3113, manufactured by the former Alaska Tire & Rubber Company of Eagle River, Alaska.
Background
This SAIB is the result of independent laboratory destructive analysis, weighing and measurement, showing that Alaskan Bushwheel Tundra Tires, serial numbers ATR006253 and ATR811227, were manufactured from unapproved ply material and rubber thinner than permitted by the approved design. Ply material containing 34 Ends Per Inch (EPI) was the only approved ply material that Alaska Tire & Rubber, could use to manufacture its tundra tires under a Technical Standard Order (TSO) Authorization issued February 26, 1997, by the Anchorage Aircraft Certification Office (ACO). Destructive analysis requested in support of Suspected Unapproved Parts Investigation 2003-00080 shows that ply material containing
27 EPI was used to manufacture the tundra tires identified by serial numbers above. Those tires were also found to weigh less than the minimum weight approved by the TSO.
The TSO approved minimum new tire weights are as follows:
· P/N 26126 = 26 lbs.
· P/N 29136 = 33.25 lbs.
· P/N 31136 = 37.75 lbs.
The actual tire weight and the minimum approved new tire weight may be compared and used as an indication of the EPI count and the thickness of rubber used to construct the tire.
The minimum used tire weights are as follows:
· P/N 26126 = 24.85 lbs.
· P/N 29136 = 31.74 lbs.
· P/N 31136 = 36.04 lbs.
The minimum used tire weights were calculated by subtracting the weight of rubber required to reduce the tread thickness to its minimum allowable thickness from the TSO approved minimum new tire weight.
Recommendation
We recommend that you weigh any Alaskan Bushwheel Tundra Tires, P/Ns 26126, 29136, and 31136, manufactured by the former Alaska Tire & Rubber Company of Eagle River, Alaska, in your possession within 100 landings after receipt of this SAIB, and replace them at your aircraft?s next annual inspection if they weigh less than the minimum weights applicable to your tires as prescribed above.
For Further Information Contact
Rodney Bahr, Aerospace Engineer, FAA Anchorage ACO, 222 W 7th Ave, Unit 14
Anchorage, AK 99513-7587; phone: (907) 271-2646, fax: (907) 271-6365;
email: rodney.bahr@faa.gov
Aircraft Certification ServiceWashington, DC
U.S. Departmentof Transportation
Federal AviationAdministration
CE-05-71July 15, 2005
http://www.faa.gov/aircraft/safety/alerts/
This is information only. Recommendations aren?t mandatory.
Introduction
This Special Airworthiness Information Bulletin (SAIB) updates information previously provided in SAIB CE-05-21, issued December 15, 2004, and provides additional safety information to you, owners and operators of airplanes equipped with Alaskan Bushwheel Tundra Tires, part numbers (P/N) 26126, 29136, and 3113, manufactured by the former Alaska Tire & Rubber Company of Eagle River, Alaska.
Background
This SAIB is the result of independent laboratory destructive analysis, weighing and measurement, showing that Alaskan Bushwheel Tundra Tires, serial numbers ATR006253 and ATR811227, were manufactured from unapproved ply material and rubber thinner than permitted by the approved design. Ply material containing 34 Ends Per Inch (EPI) was the only approved ply material that Alaska Tire & Rubber, could use to manufacture its tundra tires under a Technical Standard Order (TSO) Authorization issued February 26, 1997, by the Anchorage Aircraft Certification Office (ACO). Destructive analysis requested in support of Suspected Unapproved Parts Investigation 2003-00080 shows that ply material containing
27 EPI was used to manufacture the tundra tires identified by serial numbers above. Those tires were also found to weigh less than the minimum weight approved by the TSO.
The TSO approved minimum new tire weights are as follows:
· P/N 26126 = 26 lbs.
· P/N 29136 = 33.25 lbs.
· P/N 31136 = 37.75 lbs.
The actual tire weight and the minimum approved new tire weight may be compared and used as an indication of the EPI count and the thickness of rubber used to construct the tire.
The minimum used tire weights are as follows:
· P/N 26126 = 24.85 lbs.
· P/N 29136 = 31.74 lbs.
· P/N 31136 = 36.04 lbs.
The minimum used tire weights were calculated by subtracting the weight of rubber required to reduce the tread thickness to its minimum allowable thickness from the TSO approved minimum new tire weight.
Recommendation
We recommend that you weigh any Alaskan Bushwheel Tundra Tires, P/Ns 26126, 29136, and 31136, manufactured by the former Alaska Tire & Rubber Company of Eagle River, Alaska, in your possession within 100 landings after receipt of this SAIB, and replace them at your aircraft?s next annual inspection if they weigh less than the minimum weights applicable to your tires as prescribed above.
For Further Information Contact
Rodney Bahr, Aerospace Engineer, FAA Anchorage ACO, 222 W 7th Ave, Unit 14
Anchorage, AK 99513-7587; phone: (907) 271-2646, fax: (907) 271-6365;
email: rodney.bahr@faa.gov
