NTSB Factual Report

On July 13, 2004, about 1200 eastern daylight time, an Airbus Industrie A320-233, N951LF, operated by Ryan International Airlines, Inc., as AirTran Airways Flight 4, returned for landing after the fan cowl doors of the No. 1 engine separated from the airplane in flight in the vicinity of Atlanta, Georgia. The scheduled domestic air carrier flight was operated under the provisions of Title 14 CFR Part 121 with an instrument flight plan filed. Visual meteorological conditions prevailed. The airline transport-rated captain, airline transport-rated first officer, four flight attendants, and 104 passengers were not injured, and the airplane sustained minor damage. The flight departed Hartsfield-Jackson Atlanta International Airport, Atlanta, Georgia, at 1140 on July 13, 2004.

The captain stated he performed a preflight inspection of the airplane and noticed no irregularities. The flight departed runway 27R en route to Orlando, Florida. According to the captain, immediately after takeoff, the lead flight attendant called to inform him that a passenger reported seeing a "cover" come off the left [No. 1] engine. The captain received no cockpit indications of a problem, and the captain instructed the lead flight attendant to look out the window and verify. The captain stated he then felt the airplane "shutter," and he contacted air traffic control and requested to return for landing. The lead flight attendant confirmed to the captain the No. 1 engine fan cowl was missing. The captain stated the No. 1 engine oil quantity indicator illuminated amber, and he declared an emergency. The captain stated the engine continued to operate normally, and the flight returned for landing without further incident.

Examination of the airplane revealed both sides of the No. 1 engine fan cowl were separated, the engine pylon cantilever was bent up, aft, and inboard; and the left wing slat outboard of the engine nacelle displayed an approximate 12-inch area with dent and puncture damage. The Union City Police Department retrieved the inboard fan cowl door from a dirt roadway approximately 7.5 nautical miles west southwest of Hartsfield-Jackson Atlanta International Airport. Airport authorities found the outboard fan cowl door in the grass beside runway 27R. Examination of the latching mechanism components on each cowl door revealed no evidence of failure or mechanical malfunction. Examination of the No. 2 engine fan cowls revealed they were closed and latched.

A mechanic who performed a daily check on the airplane prior to the accident flight stated he opened the fan cowl for the No. 1 engine to check on what appeared to be an oil leak. The mechanic stated he found no leak and was in the process of closing the fan cowl when he was called away to another aircraft. The mechanic later returned to the incident airplane to finish the maintenance checks, and he stated he could not recall if the cowl doors on the No. 1 engine were fully latched.

A review of data provided by the Transportation Safety Board (TSB) of Canada revealed that, between 1991 and September 2000, there were ten similar cowl door separation events involving Airbus single-aisle aircraft series documented worldwide. According to TSB report A00O0199, "All of the occurrences happened at rotation, and in every instance the engine cowls had been opened prior to the occurrence flight."

Federal Aviation Administration Airworthiness Directive (AD) 2003-18-06 amendment 39-13297, applicable to certain models of Airbus Industrie airplanes including the A320-233, mandates the installation of a hold-open device for the cowl doors, and it mandates a modification of the latch handles to ensure that unfastened latch handles will hang down. Examination of the incident airplane revealed the handle modifications and hold-open devices were installed on the No. 1 and No. 2 engine cowls, the forward handle on each cowl was painted orange, and the three aft handles on each cowl were painted orange on the surfaces exposed when in the unlatched hanging configuration.

A review of the operator's A320/321 preflight checklist revealed it included for each engine, "Check the fan cowl doors." During examination of the incident airplane, a visual walk-around was performed with the undamaged No. 2 engine cowl in various unlatched configurations. The examination revealed unlatched cowl doors can appear closed flush upon visual walk-around inspection when the hold-open device is overridden in preparation for latching. Examination of the undamaged No. 2 engine fan cowl also revealed unfastened latches that hang down may be obscured from view by the shape of the fan cowl; the unfastened latches are visible when a specific inspection of the latches is conducted (i.e., the person conducting the inspection can view the latches by bending, crouching, or stepping back from the fan cowl).

In response to the incident, on August 5, 2004, Airbus Industrie issued an Operator's Information Telex, reference number SE 999.0088/04, to "A319/A320/A321 V2500 operators." The telex referenced the incident and stated, "the purpose of this telex is to remind all operators ... of Airbus recommendations and available modifications that have been developed to prevent fan cowl loss events." The telex recommended that, in addition to mandatory compliance with AD 2003-18-06, operators consider the following: "4.1 Maintenance Recommendations ... strictly adhere to AMM Task 71-13-00 for proper latching and closing of fan cowl doors after each maintenance action requiring cowl opening. 4.2 Operational Recommendations ... It is essential that a flight crew member visually inspects the fan cowl doors prior to each flight to ensure that they are closed and latched. 5. Improvements ... fluorescent paint on the forward cowl door latch handles (IAE SB V2500-NAC-71-0227) [and] caution decal on the outboard fan cowl doors (IAE SB V2500-NAC-71-0235)."

NTSB Probable Cause

The failure of company maintenance personnel to secure the nacelle/cowl doors, which resulted in a separation of the doors during takeoff initial climb.