Narrative:

Upon climb out from phl through about 7000 ft, I looked out the window at the engine (left) and noticed that the cowling appeared to be not properly attached. In short order I decided the best thing would be to return to phl from where I departed. I slowed the aircraft, called ATC and requested a heading back to phl and described the problem. I did not declare an emergency. Phl approach was very helpful and in about 10 mins I was on final for runway 27L. During preflight, nothing unusual was noticed about the cowlings. The mechanic later described how a cowl could be misattached by a maintenance person if close attention wasn't paid. Also, when the planes were newer, the latches had a small line inscribed on them so you could tell they are turned to a latched position. But in my case, this wouldn't have helped because the rear cowl latch hooks were missed during the closing procedure, and the latches were in the closed position. It's too bad there is no 'for sure' visual cue for the pilot to be able to tell that the actual latches are properly hooked. We pilots look for: a proper fit, safety wire, and horizontal inscripted lines (if they are there and aren't worn off). We can't actually see the hooks inside. Needless to say, the maintenance department has inscribed 'new' lines for us pilots to be able to almost guarantee cowling security. Callback conversation with reporter revealed the following information: the reporter stated the engine cowling is secured by 4 latches, 2 on each side, and the right aft latch on the left engine was not secured. The reporter said the latches are of a rotary type with no exterior visual indication that the interior hook is engaged and locked. The reporter said at each latch location safety wire is used to secure the top cowling to the lower cowling but in the aft right latch location the cowling raised about 1 inch and stretched the wire.

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Original NASA ASRS Text

Title: A B190 IN CLB AT 9000 FT RETURNED TO THE FIELD DUE TO THE L ENG R COWLING RAISED 1 INCH CAUSED BY A LATCH NOT SECURED.

Narrative: UPON CLBOUT FROM PHL THROUGH ABOUT 7000 FT, I LOOKED OUT THE WINDOW AT THE ENG (L) AND NOTICED THAT THE COWLING APPEARED TO BE NOT PROPERLY ATTACHED. IN SHORT ORDER I DECIDED THE BEST THING WOULD BE TO RETURN TO PHL FROM WHERE I DEPARTED. I SLOWED THE ACFT, CALLED ATC AND REQUESTED A HDG BACK TO PHL AND DESCRIBED THE PROB. I DID NOT DECLARE AN EMER. PHL APCH WAS VERY HELPFUL AND IN ABOUT 10 MINS I WAS ON FINAL FOR RWY 27L. DURING PREFLT, NOTHING UNUSUAL WAS NOTICED ABOUT THE COWLINGS. THE MECH LATER DESCRIBED HOW A COWL COULD BE MISATTACHED BY A MAINT PERSON IF CLOSE ATTN WASN'T PAID. ALSO, WHEN THE PLANES WERE NEWER, THE LATCHES HAD A SMALL LINE INSCRIBED ON THEM SO YOU COULD TELL THEY ARE TURNED TO A LATCHED POS. BUT IN MY CASE, THIS WOULDN'T HAVE HELPED BECAUSE THE REAR COWL LATCH HOOKS WERE MISSED DURING THE CLOSING PROC, AND THE LATCHES WERE IN THE CLOSED POS. IT'S TOO BAD THERE IS NO 'FOR SURE' VISUAL CUE FOR THE PLT TO BE ABLE TO TELL THAT THE ACTUAL LATCHES ARE PROPERLY HOOKED. WE PLTS LOOK FOR: A PROPER FIT, SAFETY WIRE, AND HORIZ INSCRIPTED LINES (IF THEY ARE THERE AND AREN'T WORN OFF). WE CAN'T ACTUALLY SEE THE HOOKS INSIDE. NEEDLESS TO SAY, THE MAINT DEPT HAS INSCRIBED 'NEW' LINES FOR US PLTS TO BE ABLE TO ALMOST GUARANTEE COWLING SECURITY. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE ENG COWLING IS SECURED BY 4 LATCHES, 2 ON EACH SIDE, AND THE R AFT LATCH ON THE L ENG WAS NOT SECURED. THE RPTR SAID THE LATCHES ARE OF A ROTARY TYPE WITH NO EXTERIOR VISUAL INDICATION THAT THE INTERIOR HOOK IS ENGAGED AND LOCKED. THE RPTR SAID AT EACH LATCH LOCATION SAFETY WIRE IS USED TO SECURE THE TOP COWLING TO THE LOWER COWLING BUT IN THE AFT R LATCH LOCATION THE COWLING RAISED ABOUT 1 INCH AND STRETCHED THE WIRE.

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.