Date: 201304
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Light: Night
Aircraft: B767-200
Operator: Air Carrier
Operating under: Part 121
Flight phase: Parked
Aircraft component: Door Window
Reporter organization: Air Carrier
Reporter function: Technician
Reporter qualification: Maintenance Airframe; Maintenance Powerplant
Human factors: Situational Awareness; Confusion; Communication Breakdown; Troubleshooting
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Maintenance
When detected: Aircraft In Service At Gate
Result: General Maintenance Action
Contributing factors: Aircraft; Manuals; Human Factors; MEL
Primary problem: MEL

Narrative: The Right Forward Door (Door 1-R) window on a B767-200 aircraft was obscured with either ice or discoloration of the acrylic [window]. It was impossible to see through the window. We tested the element of the heated pane and found an 'open' circuit. We were prepared to change the window when we were instructed to placard the Door Window Heat using B767 MEL 56-2. The only requirement of this MEL is the deactivation of the Window Heat. It fails to mention anything about the clarity of the window. I believe this is an oversight. It would be a hazard if flight attendants could not see out the door window in the advent of an evacuation. Safety is being compromised if the Window Heat is placarded 'Inoperative;' while the pane is obstructed. MEL 56-2 should require a clear/visible window for flight.

Callback: Reporter stated the Boeing B767-200 Master Minimum Equipment List (MMEL) Chapter 56-2 allows the Cabin Door Window Heat to be deactivated. His air carrier MEL Manual has the same language as the Boeing MMEL and nothing more. The cabin door windows tend to fog-up (become foggy) when the window heat is not functioning; restricting visibility out of the window.  The Aircraft Maintenance Manual (AMM) however; requires the door window to be visually clear; so that flight attendants can determine if a cabin door is safe to open in an emergency.Reporter stated the B767-200 Flight deck does not have an indicator light for Cabin Door Window Heat; no switch and no 'BITE' Test that notifies the flight crews of a window heat failure. Most of the time; the window's are written-up for being foggy; excessively scratched or crazed and then replaced. Many times the 'ground' wire for the window pane heat element becomes disconnected due to the vertical up and down movement of the door and electrical harness; which then causes the window to fog over.  His air carrier's Engineering Department agrees with him about the clear window visibility requirements; but do not want to make any changes to their MEL procedures. He was directed; but refused; to sign for the MEL 56-2 deferral citing safety concerns. Even their Maintenance Manager and Supervisor would not sign for the deferral. The aircraft was removed from service and the window replaced.



Synopsis: A Line Mechanic reports about the difference between the B767-200 Master Minimum Equipment Manual (MMEL) 56-2 that allowing for the deferral of Cabin Door Window Heat even if the door window is obscured with ice or discolored and impossible to see through. The Aircraft Maintenance Manual (AMM) however requires the door window to have clear visibility for evacuation safety.