Summary

Summary

In March 2013, the Australian Transport Safety Bureau (ATSB) received a request from the Civil Aviation Safety Authority (CASA) to assist with the non-destructive testing (NDT) and metallurgical examination of a wing spar bolt from a Beechcraft Model 35 (Bonanza) aircraft. The bolt had been removed for inspection as part of compliance activities with airworthiness directive AD/BEECH 35/67 and was reported as showing crack indications during preliminary NDT.

The ATSB was requested to examine the bolt with a view to confirming (or otherwise) the suspected cracking, and to provide commentary as to the likely contributing factors should the cracking be confirmed. To facilitate the work and provide for the issuing of a public report on conclusion of activities, the ATSB initiated an External Investigation under the provisions of the Transport Safety Investigation Act 2003.

Subsequently, the ATSB's non-destructive inspection of the bolt using both Magnetic Particle (MPI) and Fluorescent Dye Penetrant (DPI) techniques failed to reveal any indications of the reported cracking. To verify the NDT findings, the ATSB offered to conduct destructive metallurgical sectioning and metallographic examination, and in preparation for this, the wing spar bolt was returned to CASA and subsequently to the owner for re-examination to confirm the original findings.

In September 2013, following no further requests or confirmation of follow-up work, the ATSB discontinued the investigation in accordance with the provisions of section 21 (2) of the Transport Safety Investigation Act 2003.