Date: 201401
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Light: Daylight
Aircraft: A320
Operator: Air Carrier
Operating under: Part 121
Mission: Passenger
Flight phase: Parked
Aircraft component: Switch
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Technician
Reporter qualification: Maintenance Airframe; Maintenance Powerplant
Human factors: Situational Awareness; Communication Breakdown; Training / Qualification
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Maintenance
When detected: Aircraft In Service At Gate
Result: General Maintenance Action
Contributing factors: Chart Or Publication; Human Factors; Manuals; Aircraft; Procedure
Primary problem: Manuals

Narrative: [I] replaced right hand #20GA Proximity Switch. I have just been informed by Supervision that the aircraft needed [to be] jacked to check clearance of [Proximity switch] Target. The Aircraft Maintenance Manual (AMM) hyperlink to this Task was inadvertently missed due to the Airbus Aircraft Maintenance Manual (AMM) format that is hard to navigate. I was made aware of this after another aircraft had the same switch replaced and the jacking procedure was discovered.Maintenance Control stopped the aircraft in ZZZ1 to comply with jacking procedures the same day. Airbus AMM hyperlink format is not user friendly. Job specific hyperlinks are not located in the specific task being performed.

Callback: Reporter stated he replaced the Proximity 'Squat' switch on the right Main Landing Gear (MLG) of an A320 aircraft at the Line (Terminal). They had to rob (cannibalized) the switch; due to a lack of available parts at their Station; from another Airbus that was already 'Out of Service'. He used the Airbus Trouble Shooting Manual (TSM) and the Centralized Fault Display System (CFDS) to identify the cause of a 'Hard Fault' that appeared on the A320's ECAM five minutes before departure. The Proximity 'Squat' switch had failed to the'Open' position; showing 'no continuity'. Reporter stated he is more familiar with the Boeing Maintenance Manuals than the Airbus Manuals which references required Checks and Tests differently than Boeing does.  As a result; one of the maintenance pages for the Airbus Task to Remove and Replace (R/R) the proximity 'squat' switch that he had changed; also lists (includes) all the proximity switches for the right MLG.  What he did not do was to scroll down past the entire list where a Maintenance 'Note' would appear; instructing him to jack the aircraft and perform a 'gear extension'; not a gear swing; to verify the Proximity switch and 'Target' had the proper gap; or needed adjustment. The Proximity switch (sensor) is attached with two bolts and is not adjustable.Reporter stated he felt confident at the time about having corrected the discrepancy; even though he was unaware of the required MLG jacking and extension requirement check; because the BITE Tests showed the ECAM fault had cleared. When the A320 arrived at the next Maintenance Station; no jack was available to perform the Gear Extension Check. But since the aircraft did not have any inflight issues with a recurring proximity fault; Engineering allowed continued operation of the aircraft for twelve more days before a Gear Extension Check was actually accomplished.



Synopsis: A Line Aircraft Maintenance Technician (AMT) describes how a chain of events; starting with how the Airbus Aircraft Maintenance Manual (AMM) is formatted; contributed to his inadvertently missing a required Main Landing Gear (MLG) Extension Check; after replacing the right MLG Proximity 'Squat' switch on an A320 aircraft.