EASA AD US-2023-13-09
[Correction] Limit Switch and Position Transmitter Module - Repetitive Inspections
Summary
Correction to Airworthiness Directive 2023-13-09 issued by the Federal Aviation Administration (FAA) addresses all Boeing Company Model 767 airplanes. The directive mandates repetitive inspections and maintenance actions on limit switch and position transmitter modules (LSPTMs) and associated electrical wiring to prevent malfunction of horizontal stabilizer trim switches. It also requires installation of additional drain holes on certain aircraft to mitigate water accumulation risks.
What Changed
This correction republished the original AD with an editorial fix in the applicability paragraph to include the text "-300," which was omitted previously. The AD introduces repetitive inspections for immersion and blockage of LSPTMs, cleaning of drain holes, inspections for leveling compound condition, and installation of new drain holes for certain airplanes. It also adjusts inspection intervals and clarifies compliance times based on stakeholder feedback.
Why It Matters
The AD addresses a critical safety issue where water accumulation can cause LSPTMs to malfunction, potentially leading to misleading stabilizer trim position indications and hazardous flight conditions such as high-speed overruns or stalls after takeoff. Compliance ensures continued airworthiness and operational safety of Boeing 767 fleets, impacting operators, maintenance providers, and regulatory compliance teams.
What To Do
Operators of Boeing 767 airplanes must perform repetitive inspections of LSPTMs and their wiring, clean and inspect drain holes, and monitor leveling compound condition as specified. For affected airplanes, installation of two new drain holes is required. The AD is effective August 24, 2023, and inspections must be conducted at intervals not exceeding 150 days until the terminating modification is completed.
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