Narrative:

In the course of a minor repair to part of a throttle control linkage assembly on my employer's part 91 operated helicopter, I replaced 2 rivets that secure the joining of a rod end to a control rod with similar but not identical rivets called for by the manufacturer. The manufacturer called for AN470AD type rivets (by the manufacturer part number) which were not in my inventory. I used AN470AD aluminum rivets which were very similar to the rivets removed, and which fit snugly, and appeared to make a very nice repair. Other than normal attendant vibrations, the linkage is not subjected to significant torsion or longitudinal stress during flight operations. While no unsafe condition has occurred, the better, more safe practice would have been to use the manufacturer's part. The rivets used will be replaced with the manufacturer's rivets when they are received. After returning a repaired aircraft part to service, I made an appropriate entry in the aircraft logbook. I overlooked investigating an apparently intermittent failure of a piece of required equipment which had been reported to me earlier by a company pilot and which I now recall. While the pilot continued to operate the aircraft knowing I had not yet investigated the problem, the safer practice would have been to troubleshoot the reported problem before continuing flight operations. I will troubleshoot the problem as soon as possible. I reviewed a recurring airworthiness directive calling for 10 hour inspection of the tailrotor shaft bearing for wear, lubrication, etc. Since I have maintained the aircraft, I took note of this requirement and have since performed the 10 hour bearing inspection. I can say to a 95 percent certainty they were performed at least every 10 hours, because they are made by opening an easy-open access door and were made at each preflight inspection which I almost always had occasion to do at least every 10 hours of operation. However, I inadvertently overlooked the airworthiness directive requirement to log the inspections and have not routinely done so between annual inspections. While no unsafe condition has occurred because the inspections were made but not logged, it is noted that the regulations required and the safer practice is to log these inspections and I intend to do so in the future. Supplemental information from acn 210313: in the course of logging a minor repair to the throttle control linkage on my employer's part 91 operated helicopter, I entered an estimated reading from the hobbs meter because the company pilot departed with the helicopter before I had a chance to read the meter and make my aircraft log entry. While no unsafe condition occurred, the better, safer practice would have been to get an accurate hobbs meter reading at the time of repair.

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Original NASA ASRS Text

Title: AN ACFT AND PWRPLANT MECH WITH INSPECTION AUTHORIZATION WORKING FOR A FAR PART 91 HELI OP SENT IN 4 RPTS REGARDING MINOR MAINT DISCREPANCIES. THESE INCLUDED FAILING TO LOG 10 HR INSPECTIONS REQUIRED BY AN AIRWORTHINESS DIRECTIVE (THE WORK HAD BEEN DONE), INSTALLING SIMILAR RIVETS INSTEAD OF THOSE DOWN IN THE HELI PARTS MANUAL, FORGETTING TO LOG HOBBS METER ENG TIME, ALLOWING THE HELI TO BE FLOWN WITH A KNOWN DISCREPANCY, ETC.

Narrative: IN THE COURSE OF A MINOR REPAIR TO PART OF A THROTTLE CTL LINKAGE ASSEMBLY ON MY EMPLOYER'S PART 91 OPERATED HELI, I REPLACED 2 RIVETS THAT SECURE THE JOINING OF A ROD END TO A CTL ROD WITH SIMILAR BUT NOT IDENTICAL RIVETS CALLED FOR BY THE MANUFACTURER. THE MANUFACTURER CALLED FOR AN470AD TYPE RIVETS (BY THE MANUFACTURER PART NUMBER) WHICH WERE NOT IN MY INVENTORY. I USED AN470AD ALUMINUM RIVETS WHICH WERE VERY SIMILAR TO THE RIVETS REMOVED, AND WHICH FIT SNUGLY, AND APPEARED TO MAKE A VERY NICE REPAIR. OTHER THAN NORMAL ATTENDANT VIBRATIONS, THE LINKAGE IS NOT SUBJECTED TO SIGNIFICANT TORSION OR LONGITUDINAL STRESS DURING FLT OPS. WHILE NO UNSAFE CONDITION HAS OCCURRED, THE BETTER, MORE SAFE PRACTICE WOULD HAVE BEEN TO USE THE MANUFACTURER'S PART. THE RIVETS USED WILL BE REPLACED WITH THE MANUFACTURER'S RIVETS WHEN THEY ARE RECEIVED. AFTER RETURNING A REPAIRED ACFT PART TO SVC, I MADE AN APPROPRIATE ENTRY IN THE ACFT LOGBOOK. I OVERLOOKED INVESTIGATING AN APPARENTLY INTERMITTENT FAILURE OF A PIECE OF REQUIRED EQUIP WHICH HAD BEEN RPTED TO ME EARLIER BY A COMPANY PLT AND WHICH I NOW RECALL. WHILE THE PLT CONTINUED TO OPERATE THE ACFT KNOWING I HAD NOT YET INVESTIGATED THE PROBLEM, THE SAFER PRACTICE WOULD HAVE BEEN TO TROUBLESHOOT THE RPTED PROBLEM BEFORE CONTINUING FLT OPS. I WILL TROUBLESHOOT THE PROBLEM AS SOON AS POSSIBLE. I REVIEWED A RECURRING AIRWORTHINESS DIRECTIVE CALLING FOR 10 HR INSPECTION OF THE TAILROTOR SHAFT BEARING FOR WEAR, LUBRICATION, ETC. SINCE I HAVE MAINTAINED THE ACFT, I TOOK NOTE OF THIS REQUIREMENT AND HAVE SINCE PERFORMED THE 10 HR BEARING INSPECTION. I CAN SAY TO A 95 PERCENT CERTAINTY THEY WERE PERFORMED AT LEAST EVERY 10 HRS, BECAUSE THEY ARE MADE BY OPENING AN EASY-OPEN ACCESS DOOR AND WERE MADE AT EACH PREFLT INSPECTION WHICH I ALMOST ALWAYS HAD OCCASION TO DO AT LEAST EVERY 10 HRS OF OP. HOWEVER, I INADVERTENTLY OVERLOOKED THE AIRWORTHINESS DIRECTIVE REQUIREMENT TO LOG THE INSPECTIONS AND HAVE NOT ROUTINELY DONE SO BTWN ANNUAL INSPECTIONS. WHILE NO UNSAFE CONDITION HAS OCCURRED BECAUSE THE INSPECTIONS WERE MADE BUT NOT LOGGED, IT IS NOTED THAT THE REGS REQUIRED AND THE SAFER PRACTICE IS TO LOG THESE INSPECTIONS AND I INTEND TO DO SO IN THE FUTURE. SUPPLEMENTAL INFO FROM ACN 210313: IN THE COURSE OF LOGGING A MINOR REPAIR TO THE THROTTLE CTL LINKAGE ON MY EMPLOYER'S PART 91 OPERATED HELI, I ENTERED AN ESTIMATED READING FROM THE HOBBS METER BECAUSE THE COMPANY PLT DEPARTED WITH THE HELI BEFORE I HAD A CHANCE TO READ THE METER AND MAKE MY ACFT LOG ENTRY. WHILE NO UNSAFE CONDITION OCCURRED, THE BETTER, SAFER PRACTICE WOULD HAVE BEEN TO GET AN ACCURATE HOBBS METER READING AT THE TIME OF REPAIR.

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.