Airworthiness Directive E6-17187
one-timeAirworthiness Directives; Boeing Model 747-400, 777-200, and 777-300 Series Airplanes
What this AD requires
This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 747-400, 777-200, and 777-300 series airplanes. This AD requires, for certain airplanes, replacing the cell stack of the flight deck humidifier with a supplier-tested cell stack, or replacing the cell stack with a blanking plate and subsequently deactivating the flight deck humidifier. For certain other airplanes, this AD requires an inspection of the flight deck humidifier to determine certain part numbers and replacing the cell stack if necessary. This AD also allows blanking plates to be replaced with cell stacks. The actions specified by this AD are intended to prevent an increased pressure drop across the humidifier and consequent reduced airflow to the flight deck, which could result in the inability to clear any smoke that might appear in the flight deck. This action is intended to address the identified unsafe condition.
Which aircraft AD E6-17187 applies to
Whether AD E6-17187 actually applies to your aircraft (by serial and installed parts) and whether it’s already complied with comes from that aircraft’s records.
How AD compliance is recorded
A valid compliance record (14 CFR 43.9) states:
Tailplate reads a tail number’s logbooks and matches every applicable AD — including this one — to its compliance evidence, with recurring next-due dates computed.
Look up a tail number →Read the full directive (Federal Register)Applicability is derived from the FAA directive corpus and is advisory, not a legal airworthiness determination. Compliance is established only from an aircraft’s actual records.