<< >> NASA ASRS Report 801706, May 2008

While separating the exhaust case from pw 4000 engine lpt; using a support fixture; a mechanic reports the lower support knurled nut came off; causing the lpt to break loose from fixture and drop to the floor.

Attributes
ACN	801706
Time
Date	200805
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	agl single value : 0
Aircraft 1
Operator	common carrier : air carrier
Flight Phase	ground : maintenance
Person 1
Affiliation	company : air carrier
Function	maintenance : technician
ASRS Report	801706
Events
Anomaly	aircraft equipment problem : critical maintenance problem : improper maintenance other anomaly other
Independent Detector	other other : 1
Resolutory Action	none taken : detected after the fact
Consequence	other
Factors
Maintenance	contributing factor : briefing contributing factor : work cards contributing factor : engineering procedure performance deficiency : repair performance deficiency : scheduled maintenance
Supplementary
Problem Areas	Company Maintenance Human Performance Chart Or Publication
Primary Problem	Maintenance Human Performance

Narrative:

Exhaust case was removed from lpt; using support fixture. Lower saddle support knurled nut came off; leading the lpt to break loose from fixture support and lpt drop to the floor. No other known factor involved at the time. Need to make a proper job card for the procedure of splitting the exhaust case from lpt once removed from the core. And proper procedure of putting lpt in the stand. Callback conversation with reporter revealed the following information: reporter stated the secondary safety strap was disconnected to allow for the separation of the pw-4000 engine exhaust case from the low pressure turbine (lpt) section. During this disassembly; the lpt shaft is still connected to the turbine section of the lpt. Reporter stated the job card change request for better procedures are being considered by their engineering group.

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Original NASA ASRS Text

Title: WHILE SEPARATING THE EXHAUST CASE FROM PW 4000 ENG LPT; USING A SUPPORT FIXTURE; A MECHANIC REPORTS THE LOWER SUPPORT KNURLED NUT CAME OFF; CAUSING THE LPT TO BREAK LOOSE FROM FIXTURE AND DROP TO THE FLOOR.

Narrative: EXHAUST CASE WAS REMOVED FROM LPT; USING SUPPORT FIXTURE. LOWER SADDLE SUPPORT KNURLED NUT CAME OFF; LEADING THE LPT TO BREAK LOOSE FROM FIXTURE SUPPORT AND LPT DROP TO THE FLOOR. NO OTHER KNOWN FACTOR INVOLVED AT THE TIME. NEED TO MAKE A PROPER JOB CARD FOR THE PROC OF SPLITTING THE EXHAUST CASE FROM LPT ONCE REMOVED FROM THE CORE. AND PROPER PROC OF PUTTING LPT IN THE STAND. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: REPORTER STATED THE SECONDARY SAFETY STRAP WAS DISCONNECTED TO ALLOW FOR THE SEPARATION OF THE PW-4000 ENGINE EXHAUST CASE FROM THE LOW PRESSURE TURBINE (LPT) SECTION. DURING THIS DISASSEMBLY; THE LPT SHAFT IS STILL CONNECTED TO THE TURBINE SECTION OF THE LPT. REPORTER STATED THE JOB CARD CHANGE REQUEST FOR BETTER PROCEDURES ARE BEING CONSIDERED BY THEIR ENGINEERING GROUP.

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.