L ENG LOWER COWLING CAME OFF DSNDING THROUGH FL330.

Narrative

THE L ENG LOWER COWLING FELL OFF THE AIRPLANE INFLT. I NOTICED THE COWLING MISSING WHEN I GOT OUT OF THE AIRPLANE IN OKK AND PERFORMED MY POSTFLT INSPECTION. DSNDING OUT OF 33000 FT INTO OKK WE FELT A MOMENTARY RUMBLE; WHICH IS PROBABLY WHEN THE COWLING FELL OFF. THE ACFT HAD FLOWN APPROX 14 HRS SINCE THE LAST TIME THE COWLING HAD BEEN REMOVED BY MAINT. THE DIRECTOR OF OPS WAS NOTIFIED IMMEDIATELY UPON LNDG AT OKK. THE REASON FOR THE EVENT IS UNK. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED HE WAS FLYING A LEAR 24. THERE WAS AN AIRWORTHINESS DIRECTIVE ON THIS MODEL ACFT FOR THIS PROB. THE AIRWORTHINESS DIRECTIVE NOTE WAS COMPLIED WITH ON THIS ACFT. THE ACFT HAD FLOWN 12-13 HRS DURING THE 24 HR PERIOD PRIOR TO LOSING THE COWLING. THE COWLING WAS LATCHED PROPERLY AND HAD NOT BEEN UNLATCHED OVER THE PAST 24 HRS. THE SPOILERS WERE OUT AND THE SPD WAS AN ESTIMATED .77 MACH WHEN THE COWL CAME OFF. BY DESIGN THE EXTENDED SPOILERS DEFLECT THE FULL FORCE OF THE WING AIRFLOW RIGHT AT THE LOST PORTION OF THE COWLING. THE COMPANY HAS ABOUT 20 LEAR JETS AND ABOUT 12 OF THIS MODEL 24. THEY ARE FLOWN ABOUT 1000 HRS PER YR. THIS COMPANY HAS BEEN OPERATING FOR ABOUT 20 YRS WITH LEAR JETS AND HAS NOT HAD ANY PRIOR PROBS WITH THE COWLING.