Narrative:

The aircraft was returned to service after an inspection with no outstanding discrepancies. It was realized several days later that the emergency power supplies batteries had not been inspected for 3 month discharge/recharge requirement. The emergency power supplies were operable, but outside of the 3 month interval. The airframe 6 month and 12 month inspection checklists have an item for the emergency power supplies. The 200 and the 400 hour inspection checklists do not require checking the power supplies. The 6 month, 12 month, 200 and 400 hour airframe inspections often do not coincide. In this case, nothing on the airframe inoperative form brought anyone's attention to the 2 power supplies. Our in-house computer, following of inspection items was not available at the time a check was made for other items that may be due. The battery packs in the power supplies are often taken care of by the operator at their home base since the 90 day interval falls in between the 6 month inspections. We usually pull the power supplies and check their last inspection date. This time we forgot and nothing flagged it until the computer found a disagreement. Our follow-up found what had really happened. Loaner power supplies were shipped to the customer so he could continue his flight. We have reviewed how this happened and were surprised. All personnel involved are aware of the chain of events and how to break the chain.

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Original NASA ASRS Text

Title: GA LTT WAS FLOWN BEYOND THE REQUIRED MAINTENANCE INSPECTION INTERVAL.

Narrative: THE ACFT WAS RETURNED TO SVC AFTER AN INSPECTION WITH NO OUTSTANDING DISCREPANCIES. IT WAS REALIZED SEVERAL DAYS LATER THAT THE EMER PWR SUPPLIES BATTERIES HAD NOT BEEN INSPECTED FOR 3 MONTH DISCHARGE/RECHARGE REQUIREMENT. THE EMER PWR SUPPLIES WERE OPERABLE, BUT OUTSIDE OF THE 3 MONTH INTERVAL. THE AIRFRAME 6 MONTH AND 12 MONTH INSPECTION CHKLISTS HAVE AN ITEM FOR THE EMER PWR SUPPLIES. THE 200 AND THE 400 HR INSPECTION CHKLISTS DO NOT REQUIRE CHKING THE PWR SUPPLIES. THE 6 MONTH, 12 MONTH, 200 AND 400 HR AIRFRAME INSPECTIONS OFTEN DO NOT COINCIDE. IN THIS CASE, NOTHING ON THE AIRFRAME INOP FORM BROUGHT ANYONE'S ATTN TO THE 2 PWR SUPPLIES. OUR IN-HOUSE COMPUTER, FOLLOWING OF INSPECTION ITEMS WAS NOT AVAILABLE AT THE TIME A CHK WAS MADE FOR OTHER ITEMS THAT MAY BE DUE. THE BATTERY PACKS IN THE PWR SUPPLIES ARE OFTEN TAKEN CARE OF BY THE OPERATOR AT THEIR HOME BASE SINCE THE 90 DAY INTERVAL FALLS IN BTWN THE 6 MONTH INSPECTIONS. WE USUALLY PULL THE PWR SUPPLIES AND CHK THEIR LAST INSPECTION DATE. THIS TIME WE FORGOT AND NOTHING FLAGGED IT UNTIL THE COMPUTER FOUND A DISAGREEMENT. OUR FOLLOW-UP FOUND WHAT HAD REALLY HAPPENED. LOANER PWR SUPPLIES WERE SHIPPED TO THE CUSTOMER SO HE COULD CONTINUE HIS FLT. WE HAVE REVIEWED HOW THIS HAPPENED AND WERE SURPRISED. ALL PERSONNEL INVOLVED ARE AWARE OF THE CHAIN OF EVENTS AND HOW TO BREAK THE CHAIN.

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.