Narrative:

The mechanics finished working on the aircraft 30 min before departure. The right engine fire loop tested intermittently and right main wheel brakes leaked fluid. Aircraft uncowled and panels removed to find a loose connection in the fire loop. Watched mechanic put top engine cowling in place. Preflight completed by captain and first officer prior to flight showing cowling secure. Approximately 2 min after departure a passenger brings to our attention a loose right engine panel. First officer looks out to see top right engine cowling not secured. Captain asked first officer how high cowling is separated. First officer says it's not quite right and it cracked a little. After considering weight of aircraft (600-700 pounds over landing weight) we returned for landing. At touch down or shortly after main wheels touch there's a loud bang and shaking and vibration from right side of aircraft. Captain says I think we blew tires. First officer looks out and says we lost the engine cowling. We clear the runway and captain announces to tower we think we lost the engine cowling on the runway. We taxi to gate and deplane passenger. Upon further inspection we notice 2 propeller blades are broken off at the base as well as the top engine cowling is gone. Crew was told second hand that upon touchdown the cowling popped up in the air. At no time did we consider that the cowling might go into (forward) the propeller. The things we considered were 1) land before we lose the cowling airborne. 2) over gross landing weight (soft landing needed 300 FPM descent rate) 3) the risk of blowing tires at landing due to weight and speed. What I think happened: as soon as we touched down the cowling popped up at the same time as the propellers were flattened (ground fine but not reverse) out and it sucked the cowling into the propeller. Things not considered: 1) that ground fine (propeller position) could suck anything forward at 100 KTS airspeed on the ground. Things I might do differently in same situation: 1) not use ground fine (propeller aerodynamic braking) to slow aircraft on runway. 2) more thorough preflight and inspection of areas known to be worked on by mechanic prior to flight. 3) look at cowl lock arrows more closely. Other problems and considerations: 1) cowl locking arrows on locking nut does not always show mechanism locked. 2) arrows worn off, cover with exhaust soot, not in proper position when locked. 3) shutting down or feathering engine on loose cowling side could have prevented cowl propeller problem but could have caused in-flight problems at near gross weight. Didn't want to shut down an engine producing thrust.

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Original NASA ASRS Text

Title: COWLING CAME LOOSE IN FLT AND CAME OFF ON THE SUBSEQUENT RETURN FOR LNDG AND WENT THROUGH THE PROP.

Narrative: THE MECHS FINISHED WORKING ON THE ACFT 30 MIN BEFORE DEP. THE R ENG FIRE LOOP TESTED INTERMITTENTLY AND R MAIN WHEEL BRAKES LEAKED FLUID. ACFT UNCOWLED AND PANELS REMOVED TO FIND A LOOSE CONNECTION IN THE FIRE LOOP. WATCHED MECH PUT TOP ENG COWLING IN PLACE. PREFLT COMPLETED BY CAPT AND FO PRIOR TO FLT SHOWING COWLING SECURE. APPROX 2 MIN AFTER DEP A PAX BRINGS TO OUR ATTN A LOOSE R ENG PANEL. FO LOOKS OUT TO SEE TOP R ENG COWLING NOT SECURED. CAPT ASKED FO HOW HIGH COWLING IS SEPARATED. FO SAYS IT'S NOT QUITE R AND IT CRACKED A LITTLE. AFTER CONSIDERING WT OF ACFT (600-700 LBS OVER LNDG WT) WE RETURNED FOR LNDG. AT TOUCH DOWN OR SHORTLY AFTER MAIN WHEELS TOUCH THERE'S A LOUD BANG AND SHAKING AND VIBRATION FROM R SIDE OF ACFT. CAPT SAYS I THINK WE BLEW TIRES. FO LOOKS OUT AND SAYS WE LOST THE ENG COWLING. WE CLR THE RWY AND CAPT ANNOUNCES TO TWR WE THINK WE LOST THE ENG COWLING ON THE RWY. WE TAXI TO GATE AND DEPLANE PAX. UPON FURTHER INSPECTION WE NOTICE 2 PROP BLADES ARE BROKEN OFF AT THE BASE AS WELL AS THE TOP ENG COWLING IS GONE. CREW WAS TOLD SECOND HAND THAT UPON TOUCHDOWN THE COWLING POPPED UP IN THE AIR. AT NO TIME DID WE CONSIDER THAT THE COWLING MIGHT GO INTO (FORWARD) THE PROP. THE THINGS WE CONSIDERED WERE 1) LAND BEFORE WE LOSE THE COWLING AIRBORNE. 2) OVER GROSS LNDG WT (SOFT LNDG NEEDED 300 FPM DSCNT RATE) 3) THE RISK OF BLOWING TIRES AT LNDG DUE TO WT AND SPD. WHAT I THINK HAPPENED: AS SOON AS WE TOUCHED DOWN THE COWLING POPPED UP AT THE SAME TIME AS THE PROPS WERE FLATTENED (GND FINE BUT NOT REVERSE) OUT AND IT SUCKED THE COWLING INTO THE PROP. THINGS NOT CONSIDERED: 1) THAT GND FINE (PROP POS) COULD SUCK ANYTHING FORWARD AT 100 KTS AIRSPD ON THE GND. THINGS I MIGHT DO DIFFERENTLY IN SAME SIT: 1) NOT USE GND FINE (PROP AERODYNAMIC BRAKING) TO SLOW ACFT ON RWY. 2) MORE THOROUGH PREFLT AND INSPECTION OF AREAS KNOWN TO BE WORKED ON BY MECH PRIOR TO FLT. 3) LOOK AT COWL LOCK ARROWS MORE CLOSELY. OTHER PROBS AND CONSIDERATIONS: 1) COWL LOCKING ARROWS ON LOCKING NUT DOES NOT ALWAYS SHOW MECHANISM LOCKED. 2) ARROWS WORN OFF, COVER WITH EXHAUST SOOT, NOT IN PROPER POS WHEN LOCKED. 3) SHUTTING DOWN OR FEATHERING ENG ON LOOSE COWLING SIDE COULD HAVE PREVENTED COWL PROP PROB BUT COULD HAVE CAUSED INFLT PROBS AT NEAR GROSS WT. DIDN'T WANT TO SHUT DOWN AN ENG PRODUCING THRUST.

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.