Action
Supplemental notice of proposed rulemaking (NPRM); reopening of comment period.
Summary
We are revising an earlier proposed airworthiness directive (AD) for certain Embraer S.A. Model ERJ 170 airplanes. The NPRM proposed to supersede AD 2012-07-08, which requires revising the maintenance or inspection program to incorporate structural inspection requirements. The NPRM was prompted by a determination that more restrictive maintenance requirements and airworthiness limitations are necessary. Since the NPRM was issued, a new revision of the airworthiness limitations section (ALS) of the EMBRAER S.A. ERJ 170/175 Maintenance Review Board Report (MRBR) was issued, which contains more restrictive airworthiness limitations. This action revises the NPRM by proposing to require revising the maintenance or inspection program, as applicable, to incorporate the new ALS of the MRBR. This supplemental NPRM (SNPRM) would also remove certain airplanes from the applicability. In addition, we propose to supersede AD 2006-06-09, AD 2012-05-08, and AD 2012-07-08, which require tasks that are now included in the new revision of the MRBR. We are proposing this SNPRM to detect and correct fatigue cracking of various principal structural elements; such cracking could result in reduced structural integrity of the airplane. We are also proposing this SNPRM to prevent safety-significant latent failures; such failures, in combination with one or more other specified failures or events, could result in a hazardous or catastrophic failure condition of avionics, hydraulic systems, fire detection systems, fuel systems, or other critical systems. In addition, we are also proposing this SNPRM to prevent the potential for ignition sources inside fuel tanks caused by latent failures, alterations, repairs, or maintenance actions; such failures, in combination with flammable fuel vapors, could result in fuel tank explosions and consequent loss of the airplane. Since these actions impose an additional burden over those proposed in the NPRM, we are reopening the comment period to allow the public the chance to comment on these proposed changes.