Summary
We propose to adopt a new airworthiness directive (AD) for certain Embraer S.A. Model ERJ 170 and ERJ 190 airplanes. This proposed AD was prompted by reports of chafing between the auxiliary power unit (APU) electronic starter controller (ESC) power cables and the airplane tail cone firewall. This proposed AD would require a detailed inspection for damage to the insulation and inner conductors of the APU ESC power cables, installing new grommet support in the tail cone firewall, and corrective actions if necessary. We are proposing this AD to detect and correct damage to the APU ESC power cable harness, which if not corrected, could result in reduced structural integrity of the fuselage and empennage in the event of fire penetration through the firewall.