<< >> NASA ASRS Report 575678, March 2003

A lead inspector reports finding B737-700 engine driven hydraulic pump pressure lines chaffed on pylon forgings on 2 airplanes.

Attributes
ACN	575678
Time
Date	200303
Day	Fri
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	agl single value : 0
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B737-700
Operating Under FAR Part	Part 121
Flight Phase	ground : maintenance
Person 1
Affiliation	company : air carrier
Function	maintenance : lead technician
Qualification	technician : airframe technician : powerplant
ASRS Report	575678
Person 2
Affiliation	company : air carrier
Function	other personnel other
Events
Anomaly	aircraft equipment problem : critical non adherence : published procedure non adherence : far other anomaly other
Independent Detector	other other : person 1
Resolutory Action	none taken : detected after the fact
Consequence	other other other
Factors
Maintenance	contributing factor : engineering procedure performance deficiency : repair performance deficiency : inspection
Supplementary
Problem Areas	Maintenance Human Performance Aircraft Chart Or Publication Company
Primary Problem	Company

Narrative:

On mar/fri/03, I was made aware of a potential problem on the -700, pylon, engine driven hydraulic line. There have been at least 2 lines found that have been severely chaffed on the aft end behind the fitting that passes through a casting. Assembly number is 272a3151-21. Callback conversation with reporter revealed the following information: the reporter stated 2 airplanes were discovered with chaffed tubing in the pylons, and the tubing had to be replaced due to the chaffing being out of limits. The reporter said the tubing was rubbing and vibrating against a pylon support forging and was a design fault. The reporter stated engineering issued a work order to correct this problem by using a manufacturer's service bulletin, and it was noted the service bulletin was several yrs old. The reporter said all B737-700 aircraft in the fleet will have the service bulletin accomplished.

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Original NASA ASRS Text

Title: A LEAD INSPECTOR RPTS FINDING B737-700 ENG DRIVEN HYD PUMP PRESSURE LINES CHAFFED ON PYLON FORGINGS ON 2 AIRPLANES.

Narrative: ON MAR/FRI/03, I WAS MADE AWARE OF A POTENTIAL PROB ON THE -700, PYLON, ENG DRIVEN HYD LINE. THERE HAVE BEEN AT LEAST 2 LINES FOUND THAT HAVE BEEN SEVERELY CHAFFED ON THE AFT END BEHIND THE FITTING THAT PASSES THROUGH A CASTING. ASSEMBLY NUMBER IS 272A3151-21. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED 2 AIRPLANES WERE DISCOVERED WITH CHAFFED TUBING IN THE PYLONS, AND THE TUBING HAD TO BE REPLACED DUE TO THE CHAFFING BEING OUT OF LIMITS. THE RPTR SAID THE TUBING WAS RUBBING AND VIBRATING AGAINST A PYLON SUPPORT FORGING AND WAS A DESIGN FAULT. THE RPTR STATED ENGINEERING ISSUED A WORK ORDER TO CORRECT THIS PROB BY USING A MANUFACTURER'S SVC BULLETIN, AND IT WAS NOTED THE SVC BULLETIN WAS SEVERAL YRS OLD. THE RPTR SAID ALL B737-700 ACFT IN THE FLEET WILL HAVE THE SVC BULLETIN ACCOMPLISHED.

Data retrieved from NASA's ASRS site as of July 2007 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.