Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain McDonnell Douglas Model DC-9-80 series airplanes, and Model MD-88 and MD-90 airplanes. This proposal would require a one-time measurement of the length of the oxygen mask lanyards of the passenger service unit (PSU), and modification of lanyards that are longer than the proper length. This proposal is prompted by a report that the length of the oxygen mask lanyards of the PSU were found to be too long, apparently due to improper installation during production. The actions specified by the proposed AD are intended to ensure that the length of these oxygen mask lanyards is correct, so that the oxygen canister will be properly activated when needed during an emergency.