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Mechanic reports about the confusion caused by the (srm) structural repair manual data that led to his not properly evaluating a dent on the right horizontal stabilizer leading edge of a B737-400.
| Attributes | |
| ACN | 818621 |
| Time | |
| Date | 200809 |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | airport : zzz.airport |
| State Reference | US |
| Altitude | agl single value : 0 |
| Aircraft 1 | |
| Controlling Facilities | tower : zzz.tower |
| Operator | common carrier : air carrier |
| Make Model Name | B737-400 |
| Operating Under FAR Part | Part 121 |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | maintenance : technician |
| ASRS Report | 818621 |
| Events | |
| Anomaly | aircraft equipment problem : critical maintenance problem : improper maintenance maintenance problem : improper documentation non adherence : far non adherence : published procedure |
| Independent Detector | other other : 1 |
| Resolutory Action | none taken : detected after the fact |
| Consequence | other |
| Factors | |
| Maintenance | contributing factor : briefing contributing factor : manuals performance deficiency : non compliance with legal requirements performance deficiency : inspection performance deficiency : training |
| Supplementary | |
| Problem Areas | Aircraft Chart Or Publication Maintenance Human Performance |
| Primary Problem | Maintenance Human Performance |
Narrative:
Confusion caused by structural repair manual data difficult to read and evaluate. I evaluated a dent on the right-hand horizontal stabilizer leading edge on aircraft X. As stated in my log page signoff; I gave the dimensions of the dent as 3 inches long; 1.5 inches wide; and .125 inch deep. Due to the confusing data of the structural repair manual; I did not see the unmarked note on page 107 of allowable damage 1; that gives an a/Y measurement and directs you to detail viii. I first went to page 104 that directs you to paragraph 'p' for the dent. I then read the list under paragraph 'p' and came to what I then thought was the correct a/Y ratio to use. At the time I did not notice the distinctions between the zones listed. Having used what I thought was the correct a/y ratio; I was in fact using incomplete data. It was not until I was notified later about this discrepancy that I realized my error. At the time I did not realize the dent was in zone 3 and; therefore; needed further action taken. At no time did I notice that the dent possibly overlapped a rib section; until so informed. As I have already stated; the structural repair manual is extremely difficult to read and understand; so I will now seek further guidance from other sources in the future.
Original NASA ASRS Text
Title: Mechanic reports about the confusion caused by the (SRM) Structural Repair Manual data that led to his not properly evaluating a dent on the right horizontal stabilizer leading edge of a B737-400.
Narrative: Confusion caused by Structural Repair Manual data difficult to read and evaluate. I evaluated a dent on the right-hand horizontal stabilizer leading edge on Aircraft X. As stated in my log page signoff; I gave the dimensions of the dent as 3 inches long; 1.5 inches wide; and .125 inch deep. Due to the confusing data of the Structural Repair Manual; I did not see the unmarked note on Page 107 of allowable damage 1; that gives an A/Y measurement and directs you to detail viii. I first went to Page 104 that directs you to paragraph 'p' for the dent. I then read the list under paragraph 'p' and came to what I then thought was the correct A/Y ratio to use. At the time I did not notice the distinctions between the zones listed. Having used what I thought was the correct a/y ratio; I was in fact using incomplete data. It was not until I was notified later about this discrepancy that I realized my error. At the time I did not realize the dent was in Zone 3 and; therefore; needed further action taken. At no time did I notice that the dent possibly overlapped a rib section; until so informed. As I have already stated; the Structural Repair Manual is extremely difficult to read and understand; so I will now seek further guidance from other sources in the future.
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.