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-00-39 October 25, 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) alerts you, an owner or operator, of PZL Krosno KR-03a gliders of possible cracks in the fittings that attach the horizontal stabilizer to the vertical fin.
Background This SAIB is a result of two reports of cracked fittings. The first report indicates that a severed fitting was found during disassembly after an off-airport landing. While the landing incident and subsequent retrieve may have aggravated damage to the fitting (the forward fuselage was damaged), pictures of the failed fitting show rust on the fracture surface, indicating that the crack may have pre-existed the landing incident.
A second unsubstantiated report concerns a cracked but intact fitting found in Canada. The damage to this fitting was found during repairs to the glider for hangar damage.
In both cases, the damage occurred in the upper flange of the fitting, on the lug just below the bolt attach hole. This is one of the bolts that attach the horizontal stabilizer. The lower flanges are permanently attached to the top and sides of the vertical stabilizer.
The owner of the first aircraft indicates that the fitting was redesigned in 1993, doubling its thickness.
One of these revised parts has been received but cannot be installed due to improper manufacturing (the horizontal flange is located too high). This owner is currently awaiting information from the manufacturer on how to disposition this problem.
Recommendation After reviewing the data surrounding the incidents stated above, we recommend that you, an owner or operator, perform immediate inspections of the subject fittings. This inspection involves removing the horizontal stabilizer and performing visual and dye penetrent inspection of the upper flange of these fittings (see Advisory Circular 43.13-1B for inspection techniques). Part numbers of the fittings are not known at this time. If you detect any evidence of cracking, you should replace the fittings before further flight, and notify the FAA at the address listed below. You should inspect these areas on a recurring basis during annual and/or 100 hour inspections.
Note: Based on current information we, the FAA, only recommend these actions. We will continue this investigation and analyze any added information. We may require additional actions, such as the issuance of an Airworthiness Directive based on this analysis.
2 CE-00-39 We also recommend that you lift the tail using the handholds on the aft fuselage, and not lift up on the horizontal stabilizer. This is to reduce loads experienced by the fittings. You should place warning placards on the horizontal stabilizer stating “Do not lift”.
Further discussion indicates that you should be careful when attaching the horizontal stabilizer. You should line up the attaching pins or bolts properly prior to tightening the bolts. Misalignment of the pins/bolts could cause binding and potential bending of the attach fittings.
For further information, contact William O. Herderich, Aerospace Engineer, FAA, Central Region, Atlanta Aircraft Certification Office, One Crown Center, 1895 Phoenix Boulevard, Suite 450, Atlanta, GA 30349; phone
(770)-703-6082; fax (770) 703-6097; email: william.o.herderich@faa.gov.