Narrative:

No hydraulic overtemp warning. An uncorrected issue for 17 days. Plane rejected previous day for hydraulic #4 overtemp prior to takeoff; return to gate; plane rejected by captain for further flight. No repairs overnight; 18 hours available. Only work done was to move hydraulic temperature transmitter from hydraulic #4 to hydraulic #3. Problem followed; with no hydraulic temperature on EICAS; EICAS hydraulic overheat system on; and system fault on. Transmitter supplies all 3 indications of hydraulic temperature and overtemp warning from a single card per wiring prints I have. Blind redundant; poor design. MEL allowed release with zero indication of hydraulic temperature or overtemp for pilot. MEL needs change submitted to company maintenance office. Plane sat overnight about 18 hours; no repair. Transmitters available at other local companies. No part acquisition attempted. No repairs planned in ZZZ if plane left ZZZ1 not planning to send part ZZZ2 to ZZZ. Refused plane for polar operations; plan flight over airports. Refused plane also unless part shipped to ZZZ for install prior to return flight. Chief pilot X and duty manager Y did great job of arranging for part shipment to ZZZ and notified outbound captain of repairs to be made. No irregular procedures for handling engine overheat caused by hydraulic system overheating and hydraulic temperature system OTS. MEL does not distinguish all 3 temperature/overtemp indications inoperative versus only 1 or 2 and print a procedure for monitoring remaining hydraulic temperature data. MEL should not allow all 3 hydraulic temperature indications inoperative.

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Original NASA ASRS Text

Title: A B747-400 ACFT REJECTED BY PILOT DUE TO HYDRAULIC OVERTEMP WARNING SYSTEM INOP. PILOT BELIEVES MEL PROCEDURE IS INADEQUATE AND UNSAFE.

Narrative: NO HYD OVERTEMP WARNING. AN UNCORRECTED ISSUE FOR 17 DAYS. PLANE REJECTED PREVIOUS DAY FOR HYD #4 OVERTEMP PRIOR TO TKOF; RETURN TO GATE; PLANE REJECTED BY CAPT FOR FURTHER FLT. NO REPAIRS OVERNIGHT; 18 HRS AVAILABLE. ONLY WORK DONE WAS TO MOVE HYD TEMP XMITTER FROM HYD #4 TO HYD #3. PROB FOLLOWED; WITH NO HYD TEMP ON EICAS; EICAS HYD OVERHEAT SYS ON; AND SYS FAULT ON. XMITTER SUPPLIES ALL 3 INDICATIONS OF HYD TEMP AND OVERTEMP WARNING FROM A SINGLE CARD PER WIRING PRINTS I HAVE. BLIND REDUNDANT; POOR DESIGN. MEL ALLOWED RELEASE WITH ZERO INDICATION OF HYD TEMP OR OVERTEMP FOR PLT. MEL NEEDS CHANGE SUBMITTED TO COMPANY MAINT OFFICE. PLANE SAT OVERNIGHT ABOUT 18 HRS; NO REPAIR. XMITTERS AVAILABLE AT OTHER LCL COMPANIES. NO PART ACQUISITION ATTEMPTED. NO REPAIRS PLANNED IN ZZZ IF PLANE LEFT ZZZ1 NOT PLANNING TO SEND PART ZZZ2 TO ZZZ. REFUSED PLANE FOR POLAR OPS; PLAN FLT OVER ARPTS. REFUSED PLANE ALSO UNLESS PART SHIPPED TO ZZZ FOR INSTALL PRIOR TO RETURN FLT. CHIEF PLT X AND DUTY MGR Y DID GREAT JOB OF ARRANGING FOR PART SHIPMENT TO ZZZ AND NOTIFIED OUTBOUND CAPT OF REPAIRS TO BE MADE. NO IRREGULAR PROCS FOR HANDLING ENG OVERHEAT CAUSED BY HYD SYS OVERHEATING AND HYD TEMP SYS OTS. MEL DOES NOT DISTINGUISH ALL 3 TEMP/OVERTEMP INDICATIONS INOP VERSUS ONLY 1 OR 2 AND PRINT A PROC FOR MONITORING REMAINING HYD TEMP DATA. MEL SHOULD NOT ALLOW ALL 3 HYD TEMP INDICATIONS INOP.

Data retrieved from NASA's ASRS site as of January 2009 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.