Narrative:

I made a set of JT9D-7J fan blades serviceable. This set contains 46 (each) fan blades. I suspect that the locking slot at the blade root location may be oversize. The wear limits in question are the following: a) 0.210 inch maximum slot width at outboard end of slot. B) 0.240 inch maximum slot width at inboard end of slot. The final inspection on the set that I performed does not require a dimensional inspection (visual only). The piece part inspection and serviceability was completed by another inspector who I feel was not trained properly. Several days after I released the set for service, my gut instinct told me some of the fan blades might have had excessive wear in the locking slot. I checked some of the fan blades in the serviceable pool (a storage area for serviceable fan blades) and found that several fan blades had locking slot wear that was beyond serviceable limits. All of these fan blades with this condition were made serviceable by the same inspector. I am presently attempting to isolate and remove these out of tolerance fan blades for proper disposition (from fan blades presently in serviceable pool). Callback conversation with reporter revealed the following information: the reporter added the following update. He said powerplant engineering inspected the held out of service blades and were all found to be legal and within limits. He stated that powerplant engineering will publish an inspection alert to clarify the maintenance manual specifications and points to be measured.

Google
 

Original NASA ASRS Text

Title: A SET OF JT9D-7J ENG FAN BLADES WERE INSPECTED AND RELEASED AS SERVICEABLE THAT DID NOT MEET THE MAINT MANUAL WEAR LIMITS.

Narrative: I MADE A SET OF JT9D-7J FAN BLADES SERVICEABLE. THIS SET CONTAINS 46 (EACH) FAN BLADES. I SUSPECT THAT THE LOCKING SLOT AT THE BLADE ROOT LOCATION MAY BE OVERSIZE. THE WEAR LIMITS IN QUESTION ARE THE FOLLOWING: A) 0.210 INCH MAX SLOT WIDTH AT OUTBOARD END OF SLOT. B) 0.240 INCH MAX SLOT WIDTH AT INBOARD END OF SLOT. THE FINAL INSPECTION ON THE SET THAT I PERFORMED DOES NOT REQUIRE A DIMENSIONAL INSPECTION (VISUAL ONLY). THE PIECE PART INSPECTION AND SERVICEABILITY WAS COMPLETED BY ANOTHER INSPECTOR WHO I FEEL WAS NOT TRAINED PROPERLY. SEVERAL DAYS AFTER I RELEASED THE SET FOR SVC, MY GUT INSTINCT TOLD ME SOME OF THE FAN BLADES MIGHT HAVE HAD EXCESSIVE WEAR IN THE LOCKING SLOT. I CHKED SOME OF THE FAN BLADES IN THE SERVICEABLE POOL (A STORAGE AREA FOR SERVICEABLE FAN BLADES) AND FOUND THAT SEVERAL FAN BLADES HAD LOCKING SLOT WEAR THAT WAS BEYOND SERVICEABLE LIMITS. ALL OF THESE FAN BLADES WITH THIS CONDITION WERE MADE SERVICEABLE BY THE SAME INSPECTOR. I AM PRESENTLY ATTEMPTING TO ISOLATE AND REMOVE THESE OUT OF TOLERANCE FAN BLADES FOR PROPER DISPOSITION (FROM FAN BLADES PRESENTLY IN SERVICEABLE POOL). CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR ADDED THE FOLLOWING UPDATE. HE SAID POWERPLANT ENGINEERING INSPECTED THE HELD OUT OF SERVICE BLADES AND WERE ALL FOUND TO BE LEGAL AND WITHIN LIMITS. HE STATED THAT POWERPLANT ENGINEERING WILL PUBLISH AN INSPECTION ALERT TO CLARIFY THE MAINT MANUAL SPECS AND POINTS TO BE MEASURED.

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.