Action
Supplemental notice of proposed rulemaking (SNPRM); reopening of comment period.
Summary
We are revising an earlier proposed airworthiness directive (AD) that proposed to supersede AD 2006-22-15 for all The Boeing Company Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747- 200F, 747-300, 747-400, 747-400D, 747-400F, 747SR, and 747SP series airplanes. AD 2006-22-15 requires repetitive inspections for cracking of certain panel webs and stiffeners of the nose wheel well (NWW), and corrective actions if necessary; and replacement of certain panels with new panels, which terminates the repetitive inspections. The notice of proposed rulemaking (NPRM) proposed to reduce a compliance time and add certain inspections and applicable repair. The NPRM was prompted by reports of fatigue cracking in the panel webs and stiffeners of the NWW found prior to the inspection threshold of AD 2006-22-15. This action revises the NPRM by specifying a repetitive inspection interval for a certain NWW area inspection. We are proposing this SNPRM to prevent fatigue cracking of the NWW side and top panels, which could result in a NWW depressurization event severe enough to reduce the structural integrity of the fuselage. Since these actions impose an additional burden over that proposed in the NPRM, we are reopening the comment period to allow the public the chance to comment on these proposed changes.