PROP SPINNER SHATTERED IN FLT. CONTINUED TRAINING.

Narrative

VFR UNDER THE CTL OF DENVER APCH CTL FOR PRACTICE INSTRUMENT APCHS AT APA. WHILE CRUISING AT APPROX 8000 FT MSL (2 INCH MANIFOLD PRESSURE AND 2450 RPM); WE HEARD A LOUD 'THUMP'. IMMEDIATELY SUSPECTING A BIRD STRIKE (OF ABOUT THE SIZE OF A CROW OR HAWK); WE CHKED ENG INSTRUMENTS; INSPECTED THE ACFT VISUALLY FROM INSIDE THE COCKPIT AND CHKED FLT CTL EFFECTIVENESS. WE OBSERVED NO DEVS FROM NORMAL AT THAT TIME. WE CONTINUED THE INSTRUMENT TRAINING FLT; MAKING 2 ILS APCHS TO RWY 35R AT APA. THE FIRST ILS APCH TERMINATED IN A MISSED APCH AND THE SECOND ILS APCH TERMINATED IN A FULL STOP LNDG. OUR LNDG AT APA WAS SUCCESSFUL WITHOUT INCIDENT. AFTER WE TAXIED OFF RWY 35R; THE ENG QUIT; PROBABLY BECAUSE THE PWR WAS BROUGHT BACK TOO MUCH. WE WERE NOT ABLE TO RESTART THE ENG WHILE IT WAS HOT. THE BATTERY WAS NOT PARTICULARLY WELL CHARGED. I EXITED THE ACFT; OBTAINED A TOW BAR AND FASTENED IT TO THE NOSE LNDG GEAR. AT THAT TIME I NOTICED THAT THE SPINNER HAD PARTIALLY DISINTEGRATED; LEAVING ONLY 4 OR SO INCHES OF SPINNER LOOSELY ATTACHED ONLY AT ITS VERY CENTER SINCE THE OUTER PORTION HAD TORN OFF AND DISAPPEARED. ONE OF THE PROP BLADES HAD 2 NICKS IN IT -- APPARENTLY CAUSED BY IT STRIKING THE PORTION OF THE SPINNER THAT HAD SEPARATED FROM THE ACFT. FURTHER INSPECTION OF THE ACFT REVEALED NO OTHER DAMAGE AND NO REMNANTS OF BIRD PARTS SUCH AS BLOOD OR FEATHERS. I CONCLUDED THAT 'THUMP' NOISE HEARD WAS THE SOUND OF THE SPINNER DISINTEGRATING AND/OR ITS SEPARATED PART BEING STRUCK BY THE PROP BLADE. WE PARKED THE ACFT AT APA TO BE SUBSEQUENTLY INSPECTED (AND REPAIRED) BY QUALIFIED ACFT MAINT PERSONNEL. WE CEASED FLT OPS WITH THE ACFT AT THAT TIME. WHEN THE ACFT WAS PREFLTED; A SMALL CRACK WAS NOTICED IN THE SPINNER NEAR ONE OF THE ATTACHMENT SCREWS. WE DID NOT REALIZE THE POTENTIAL FOR DAMAGE THAT A CRACK OF THAT SIZE POSED; THE ACFT'S OWNER RPTEDLY KNEW OF THE CRACK'S EXISTENCE AND DID NOT BELIEVE THAT IT WAS ANY PROBLEM. WHEN HEARING THE 'THUMP' WHILE IN FLT; WE MISTAKENLY BELIEVED THAT IT WAS CAUSED BY A BIRD STRIKE THAT CAUSED NO DAMAGE TO THE ACFT. EVEN THOUGH NO ADDITIONAL DAMAGE AND NO INJURIES RESULTED FROM THE INCIDENT; IN RETROSPECT I BELIEVE THAT IT WOULD HAVE BEEN MORE PRUDENT FOR US TO HAVE LANDED THE ACFT AT APA IMMEDIATELY AFTER COMPLETING THE FIRST INSTRUMENT APCH; RATHER THAN PERFORMING A MISSED APCH AND DOING THE SECOND INSTRUMENT APCH AS WELL. WE WERE QUITE FORTUNATE THAT THE NICKS IN THE PROP BLADE DID NOT CAUSE ITS CATASTROPHIC FAILURE WITH A RESULTING TEARING OF THE ACFT ENG FROM ITS MOUNTS AND A CRASH OF THE ACFT.