Narrative:

The chief had compression problems on 1 cylinder and the cowl had to be removed for maintenance. The propeller must be removed to take the nose bowl off a chief. After engine repair; the cowl was reinstalled and the propeller placed on the tapered shaft to check for rubbing. The spinner; a large spinner required (although completely unnecessary) because the airplane once had a hand-cranked starter; was installed because it is the first thing to rub if the cowl is not on perfectly. It rubbed; so the cowl had to be loosened and retightened until everything had sufficient clearance. The engine was test run and the airplane appeared ready for flight; even though the propeller; which was only placed on the shaft to test for clearance; had not been tightened or safetied. The spinner prevented this from being noticed before flight. The engine tested fine in the pretkof check; and the flight proceeded normally for about 30 mins until a knocking sound was noticed. Power was reduced; and the propeller departed the airplane and landed; as best we can tell; in a woods north of the airport. We do not know for sure; as we have not yet found it. The chief glided back to the airport and landed with no problems and no damage. Overly restrictive regulations that prevent a common-sense substitution of an inexpensive skull-cap spinner like nearly every other chief; champ and cub with this engine have contributed to this event; but the cause was distraction with the cowl and resultant oversight of the propeller's improper attachment. The problems that could result from not securely attaching the propeller before flight are obvious; and unless this becomes more than an isolated event action to prevent further occurrences would not seem necessary. I know it will not happen again with anything I am flying.

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Original NASA ASRS Text

Title: FAILURE TO PROPERLY RE-SECURE THE PROP AFTER COWLING MAINT OF AN AERONCA 11AC RESULTS IN ITS LOSS DURING A TEST FLT. ACFT LANDS SAFELY; PROP STILL MISSING.

Narrative: THE CHIEF HAD COMPRESSION PROBS ON 1 CYLINDER AND THE COWL HAD TO BE REMOVED FOR MAINT. THE PROP MUST BE REMOVED TO TAKE THE NOSE BOWL OFF A CHIEF. AFTER ENG REPAIR; THE COWL WAS REINSTALLED AND THE PROP PLACED ON THE TAPERED SHAFT TO CHK FOR RUBBING. THE SPINNER; A LARGE SPINNER REQUIRED (ALTHOUGH COMPLETELY UNNECESSARY) BECAUSE THE AIRPLANE ONCE HAD A HAND-CRANKED STARTER; WAS INSTALLED BECAUSE IT IS THE FIRST THING TO RUB IF THE COWL IS NOT ON PERFECTLY. IT RUBBED; SO THE COWL HAD TO BE LOOSENED AND RETIGHTENED UNTIL EVERYTHING HAD SUFFICIENT CLRNC. THE ENG WAS TEST RUN AND THE AIRPLANE APPEARED READY FOR FLT; EVEN THOUGH THE PROP; WHICH WAS ONLY PLACED ON THE SHAFT TO TEST FOR CLRNC; HAD NOT BEEN TIGHTENED OR SAFETIED. THE SPINNER PREVENTED THIS FROM BEING NOTICED BEFORE FLT. THE ENG TESTED FINE IN THE PRETKOF CHK; AND THE FLT PROCEEDED NORMALLY FOR ABOUT 30 MINS UNTIL A KNOCKING SOUND WAS NOTICED. PWR WAS REDUCED; AND THE PROP DEPARTED THE AIRPLANE AND LANDED; AS BEST WE CAN TELL; IN A WOODS N OF THE ARPT. WE DO NOT KNOW FOR SURE; AS WE HAVE NOT YET FOUND IT. THE CHIEF GLIDED BACK TO THE ARPT AND LANDED WITH NO PROBS AND NO DAMAGE. OVERLY RESTRICTIVE REGS THAT PREVENT A COMMON-SENSE SUBSTITUTION OF AN INEXPENSIVE SKULL-CAP SPINNER LIKE NEARLY EVERY OTHER CHIEF; CHAMP AND CUB WITH THIS ENG HAVE CONTRIBUTED TO THIS EVENT; BUT THE CAUSE WAS DISTR WITH THE COWL AND RESULTANT OVERSIGHT OF THE PROP'S IMPROPER ATTACHMENT. THE PROBS THAT COULD RESULT FROM NOT SECURELY ATTACHING THE PROP BEFORE FLT ARE OBVIOUS; AND UNLESS THIS BECOMES MORE THAN AN ISOLATED EVENT ACTION TO PREVENT FURTHER OCCURRENCES WOULD NOT SEEM NECESSARY. I KNOW IT WILL NOT HAPPEN AGAIN WITH ANYTHING I AM FLYING.

Data retrieved from NASA's ASRS site as of January 2009 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.