Summary
We propose to adopt a new airworthiness directive (AD) for the products listed above that would supersede an existing AD. This proposed AD results from mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as:
A case was reported where the NLG leg of a DA 40 aircraft failed in the area of the nose gear leg pivot axle. The affected airplane was mostly operated on grass runways and used for training operations. The investigation showed that the failure was due to a fatigue crack that had developed in the pivot axle. Subsequent material inspections determined that these cracks may also develop on other aircraft, depending on the type of operation. This condition, if not detected and corrected, could lead to further cases of NLG failure, possibly causing damage to the aircraft and injuries to occupants. To address and correct this unsafe condition, ACG issued AD A-2005-005 to require repetitive inspections of the NLG leg and, in case cracks are found, replacement of the NLG leg with a serviceable unit. Since that AD was issued, Diamond Aircraft Industries developed a redesigned NLG leg which is not affected by the cracking phenomenon addressed by AD A-2005-005.
The proposed AD would require actions that are intended to address the unsafe condition described in the MCAI.