Narrative:

While on a local proficiency flight, I returned to the airport area for landing to find I had no hydraulic system. Both gear and flaps are hydraulically pwred. After doing all the troubleshooting I could, I referred to the emergency procedure to extend the gear by accumulator pressure. Unfortunately, the system fluid was gone and the procedure did not work. The aircraft was successfully 'bellied in.' there were no injuries, and the airplane suffered only minor damage. Later investigation showed that the hydraulic reservoir cap had blown out of the filler neck. Apparently, it had vibrated free. The hydraulic filler on this aircraft is very difficult to reach and is obstructed by several cable bundles making the complicated cap difficult to secure properly. I put the primary cause of this mishap down to improper preflight. I take the blame for this act of complacency. I had never had trouble with the hydraulic cap in the past, and didn't really think this was a vulnerability. Guess I was wrong!

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Original NASA ASRS Text

Title: JET TRAINER PLT LANDED THE ACFT GEAR UP AFTER THE ACFT HYD SYS FAILED. THE PLT DID NOT DO A PROPER PREFLT INSPECTION OF THE ACFT.

Narrative: WHILE ON A LCL PROFICIENCY FLT, I RETURNED TO THE ARPT AREA FOR LNDG TO FIND I HAD NO HYD SYS. BOTH GEAR AND FLAPS ARE HYDRAULICALLY PWRED. AFTER DOING ALL THE TROUBLESHOOTING I COULD, I REFERRED TO THE EMER PROC TO EXTEND THE GEAR BY ACCUMULATOR PRESSURE. UNFORTUNATELY, THE SYS FLUID WAS GONE AND THE PROC DID NOT WORK. THE ACFT WAS SUCCESSFULLY 'BELLIED IN.' THERE WERE NO INJURIES, AND THE AIRPLANE SUFFERED ONLY MINOR DAMAGE. LATER INVESTIGATION SHOWED THAT THE HYD RESERVOIR CAP HAD BLOWN OUT OF THE FILLER NECK. APPARENTLY, IT HAD VIBRATED FREE. THE HYD FILLER ON THIS ACFT IS VERY DIFFICULT TO REACH AND IS OBSTRUCTED BY SEVERAL CABLE BUNDLES MAKING THE COMPLICATED CAP DIFFICULT TO SECURE PROPERLY. I PUT THE PRIMARY CAUSE OF THIS MISHAP DOWN TO IMPROPER PREFLT. I TAKE THE BLAME FOR THIS ACT OF COMPLACENCY. I HAD NEVER HAD TROUBLE WITH THE HYD CAP IN THE PAST, AND DIDN'T REALLY THINK THIS WAS A VULNERABILITY. GUESS I WAS WRONG!

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.