B767 captain reports missing fasteners on engine pylons which is not uncommon in his experience.

Attributes
ACN	790210
Time
Date	200806
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	agl single value : 0
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B767-300 and 300 ER
Operating Under FAR Part	Part 121
Flight Phase	ground : preflight
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Experience	flight time last 90 days : 230 flight time total : 16300 flight time type : 3500
ASRS Report	790210
Events
Anomaly	aircraft equipment problem : less severe maintenance problem : improper maintenance
Independent Detector	other flight crewa
Consequence	other
Supplementary
Problem Areas	Maintenance Human Performance Aircraft
Primary Problem	Ambiguous

Narrative:

Upon preflight walkaround I found 5 fasteners missing; 3 on the right engine inboard engine pylon. Maintenance was notified. 2 were replaced immediately; but the 3 on the engine pylon had missing nut plates. Much time was lost determining if they had to be replaced or could be deferred. They ended up replacing them. The result was a 1 hour 39 min delay. There are a significant number of fasteners backing out over a short period of time on all B767's probably due to their age and flexing in turbulence and on landing. There are multiple manual pages dealing with locations; ie; 1 for just the pylon heat shield. This takes excessive time for the mechanic to determine if the missing fastener can be deferred or must be replaced. Maintenance is not catching the missing fasteners when the aircraft come into the stations; hence they are found by the crew and can cause delays. B757's have the same problem; but tend to have fewer fasteners missing on the engine pylons. This is a bigger issue than just 1 aircraft at 1 station on 1 day.

Original NASA ASRS Text

Title: B767 CAPT REPORTS MISSING FASTENERS ON ENGINE PYLONS WHICH IS NOT UNCOMMON IN HIS EXPERIENCE.

Narrative: UPON PREFLT WALKAROUND I FOUND 5 FASTENERS MISSING; 3 ON THE R ENG INBOARD ENG PYLON. MAINT WAS NOTIFIED. 2 WERE REPLACED IMMEDIATELY; BUT THE 3 ON THE ENG PYLON HAD MISSING NUT PLATES. MUCH TIME WAS LOST DETERMINING IF THEY HAD TO BE REPLACED OR COULD BE DEFERRED. THEY ENDED UP REPLACING THEM. THE RESULT WAS A 1 HR 39 MIN DELAY. THERE ARE A SIGNIFICANT NUMBER OF FASTENERS BACKING OUT OVER A SHORT PERIOD OF TIME ON ALL B767'S PROBABLY DUE TO THEIR AGE AND FLEXING IN TURB AND ON LNDG. THERE ARE MULTIPLE MANUAL PAGES DEALING WITH LOCATIONS; IE; 1 FOR JUST THE PYLON HEAT SHIELD. THIS TAKES EXCESSIVE TIME FOR THE MECH TO DETERMINE IF THE MISSING FASTENER CAN BE DEFERRED OR MUST BE REPLACED. MAINT IS NOT CATCHING THE MISSING FASTENERS WHEN THE ACFT COME INTO THE STATIONS; HENCE THEY ARE FOUND BY THE CREW AND CAN CAUSE DELAYS. B757'S HAVE THE SAME PROB; BUT TEND TO HAVE FEWER FASTENERS MISSING ON THE ENG PYLONS. THIS IS A BIGGER ISSUE THAN JUST 1 ACFT AT 1 STATION ON 1 DAY.

Data retrieved from NASA's ASRS site as of May 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.