An ATR 42 wing-structure cracking issue thought to be a one-off case has turned up on three other aircraft, leading the OEM to issue new inspection recommendations that the European Aviation Safety Agency (EASA) plans to mandate.
"[An] occurrence was reported of detecting cracks on the wing of one in-service ATR 42 airplane in 2004," EASA explains in a proposed airworthiness directive issued Nov. 7. "The cracks were found on the upper feet of ribs and on the upper skin of the wing outer boxes."
The fleet was inspected per an ATR service bulletin that was mandated by France's DGAC. No other cracks were found, and "it was determined that these cracks were an isolated case," EASA explains. But recent reports of three other instances triggered a new ATR service bulletin, issued Oct. 19, and the EASA draft AD.
The new proposed directive orders detailed visual inspections of the left- and right-wing upper feet and upper panel between rib 24 and rib 29 on ATR 42-200s through -500s. Initial checks need to be done within 12 months or when the aircraft's service life reaches 48 months or 6,000 cycles, whichever occurs later. Follow-up checks are to be done every 48 months or 6,000 cycles, whichever comes first.
ATR's service bulletin includes repair instructions for any discrepancies found during the checks.
EASA is taking comments on the directive through Dec. 6.