A B737-800 REJECTED TKOF DUE TO THE HEADS UP DISPLAY (HUD) COMBINER FALLING FROM THE STOWED POS; IMPAIRING VISION. INTERIM REPAIR MADE TO STOW LATCH.

Narrative

MAR/WED/02; ACFT X DID A REJECTED TKOF AT ZZZ. ON RETURN TO THE GATE; THE CAPT EXPLAINED TO ME THAT THE HEADS UP DISPLAY (HUD) COMBINER FELL FROM THE STOWED POS DURING HIS TKOF ROLL AND BLOCKED A SIGNIFICANT PORTION OF HIS VISION. I INSPECTED THE LATCHING MECHANISM FOR THE COMBINER AND FOUND THAT THE LATCHING PIN HAD LOST ITS SPRING TENSION ALLOWING THE PIN TO VIBRATE OUT DURING TKOF. I CALLED MAINT CTL AND INFORMED THE CTLR WHAT I HAD FOR A PROB. WE DISCUSSED ALTERNATE MEANS OF SECURING THE COMBINER FROM FALLING INTO THE VIEW OF THE CAPT. IT WAS AGREED TO TY-WRAP THE COMBINER IN THE STOWED POS AND MEL THE HUD; WHICH WAS DONE AND DOCUMENTED IN THE ACFT LOG. IN RETROSPECT; I MEL'ED THE HUD PER 34-44-00; WHICH ALLOWS FOR AN INOP SYS BUT I HAD NO APPROVED PROCS FOR USING AN ALTERNATE MEANS FOR SECURING THE COMBINER IN THE STOWED POS. INITIALLY; I THOUGHT I WAS DOING THE RIGHT THING. I HAD DISCUSSED THE PROB WITH MAINT CTL; AND THE CAPT AND WE ALL FELT THAT INSTALLING A TY-WRAP WOULD SECURE THE COMBINER. JUST TO BE ON THE SAFE SIDE; I ADDED A SECOND TY-WRAP. WE HAD A FULL FLT AND THE DIRECTOR OF LINE MAINT WAS LOOKING OVER MY SHOULDER DURING THE WHOLE PROCESS. NO PRESSURE. THERE IS 1 ISSUE HERE: WE HAVE A DEFECTIVE PART THAT NEEDS TO BE IMPROVED EITHER THROUGH ENGINEERING OR MANUFACTURING IMPROVEMENT. THAT SHOULD NOT BE TOO HARD TO FIX. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE COMBINER IS AN 8 INCH BY 5 INCH PLASTIC SHEET THAT PROVIDES RWY DISPLAYS AND SOME INSTRUMENTATION WHEN FOLDED DOWN IN FRONT OF THE WINDSHIELD. THE RPTR SAID THE COMBINER IS STOWED OUT OF VIEW WITH A SPRING TENSION LATCH WHICH IS POORLY DESIGNED. THE RPTR STATED THIS SPRING LATCH FAILED AND ALLOWED THE COMBINER TO DROP INTO VIEW IMPAIRING THE CAPT'S VISION. THE RPTR STATED THE HUD CAN BE DEFERRED PER THE MEL; BUT GIVES NO SPECIAL PROCS ON HOW TO SECURE OR DEACTIVATE THE COMBINER. THE RPTR SAID 2 TY-WRAPS WERE USED TO LOCK THE COMBINER OUT OF VIEW. THE RPTR STATED THE USE OF THE TY-WRAPS AND THE MEL NOT GIVING ANY GUIDANCE ON DEACTIVATION MAY HAVE BEEN AN FAR VIOLATION. THE RPTR SAID IN THIS REG CLIMATE; COMMON SENSE HAS NO VALUE AND; IF IT IS NOT WRITTEN IN SOME APPROVED DOCUMENTS; IT'S A NO-GO ITEM.