Narrative:

Recurring airworthiness directive note on fuel cell system on C421 due every 600 hours. I was unaware of this airworthiness directive note. We exceeded the hours by +20 hours. Shop missed this but caught the problem on 50 hour inspection.

Google
 

Original NASA ASRS Text

Title: A C421 WENT 20 HRS OVERTIME ON A REQUIRED AIRWORTHINESS DIRECTIVE RECURRING 600 HR FUEL CELL SYS INSPECTION.

Narrative: RECURRING AIRWORTHINESS DIRECTIVE NOTE ON FUEL CELL SYS ON C421 DUE EVERY 600 HRS. I WAS UNAWARE OF THIS AIRWORTHINESS DIRECTIVE NOTE. WE EXCEEDED THE HRS BY +20 HRS. SHOP MISSED THIS BUT CAUGHT THE PROB ON 50 HR INSPECTION.

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.