Summary
The FAA proposes to supersede an existing airworthiness directive (AD) that applies to all Model 767 airplanes. The existing AD currently requires repetitive detailed and high frequency eddy current (HFEC) inspections of the station (STA) 1809.5 bulkhead for cracking, and corrective actions if necessary. This proposed AD would expand the inspection area to include the vertical inner chord at STA 1809.5. This proposed AD results from reported fatigue cracking in the vertical inner chord and the forward outer chord while doing the detailed inspection of the horizontal inner chord at STA 1809.5. We are proposing this AD to detect and correct fatigue cracking in the bulkhead structure at STA 1809.5 and the vertical inner chord at STA 1809.5, which could result in failure of the bulkhead structure for carrying the flight loads of the horizontal stabilizer, and consequent loss of controllability of the airplane.