NTSB Factual Report

On April 22, 2007, at 0624 eastern daylight time, an Airbus A319-111, N904FR, Frontier Flight 851, operating as a 14 CFR Part 121 scheduled domestic passenger flight, registered to RBS Aerospace Limited, operated by Frontier Airlines, Inc, experienced a loss of the right lower engine cowling on initial climb out at 200 feet, and the loss of the yellow hydraulic pressure system. The flight crew leveled the airplane off at 3,000 feet and declared an emergency. The flight was cleared for an approach to runway 9 left and landed with out further incident at the William B. Hartsfield Atlanta International Airport, Atlanta, Georgia at 0642. Visual meteorological conditions prevailed and an instrument flight rules flight plan was filed. The airplane received minor damaged. The airline transport rated pilot-in-command (PIC), first officer (FO), three flight attendants, and one hundred twenty four passengers reported no injuries. The flight was originating from the William B. Hartsfield International Airport, Atlanta, Georgia, on April 22, 2007; at 0624.The planned destination airport was Denver International Airport, Denver, Colorado.

The PIC stated the flight deck crew arrived at the airplane at the required show time. The gate agent informed them that a mechanic was working on the brakes. The PIC and FO went down to the airplane and did not see anyone and the logbook was not on the flight deck. The FO departed the flight deck, completed the walk around inspection, and observed nothing unusual. A short time later the mechanic brought the logbook to the flight deck and explained to the PIC that he had worked on the No.1 brake and placed the temperature sensor on the minimum equipment list.

Examination of the airplane right engine lower engine cowling by an FAA inspector after the incident revealed all three latches were in the unlocked position. The latch fitting on the aft position was missing and the bolt that secures it was broken. The two forward fittings were in good condition and showed no signs of stress.

Review of Frontier Flight Operations Manual-Volume II, Exterior Inspection, General, states, "The exterior inspection is normally performed by the first officer unless briefed otherwise by the captain. This check ensures that the overall condition of the aircraft and its visible components and equipment are safe for flight. A complete exterior inspection must be performed by a flight crewmember before each originating flight." The Exterior Walk Around Inspection states in item 7, "ENG LH SIDE....-* Fan cowl doors, CLOSED/LATCHED. The checklist further states in item 19, "ENG RH SIDE....-*Fan cowl doors, CLOSED/LATCHED." The A319 STANDARD OPERATING PROCEDURES EXTERIOR INSPECTION states in GENERAL, "The exterior inspection ensures that the overall condition of the aircraft and its visible components and equipment are safe for the flight. Complete inspection is normally performed by maintenance personnel or in the absence of maintenance personnel by a flight crewmember before each originating flight. Items marked by asterisks (*) must be performed by a flight crewmember before each flight." Item 7, ENG 2 LH SIDE, and item 19, ENG 2 RH SIDE both have an asterisk next to Fan cowl doors, CLOSED/LATCHED."

Review of FRONTIER AIRCRAFT FLIGHT LOG for Aircraft Number 904 revealed the Integrated Drive Generator (IDG) required servicing on April 22, 2007. The mechanic signed off on the FRONTIER AIRCRAFT MAINTENANCE NON-ROUTINE SUPPLEMENT SHEET on April 22, 2007, "Serviced #2 IDG IAW AMM 24-21-00-03-02." The FRONTIER MAINTENANCE LINE CHECK LIST, HEAVY SERVICE, CARD No. HS 2010-1, dated February 26, 2007 states on page 7 item 15.1, "Cowlings: panels, air outlets, security of latches." The mechanic indicated with his initials and social security number that this task had been complied with on April 22, 2007. The mechanic entered his initials and social security number on page 12 item 20.1 stating, "Endorse corrective actions in technical log book and sign against each corrected or carried forward item."

Review of the airplane log books revealed the airplane was equipped with the modifications outlined in AD2003-18-6 and amendment 39-13297, which mandates the installation of a hold open device for the cowl doors as well as a modification of the latch handles to ensure that the unfastened latch handle will hang down.

Airbus previously issued a Operator's Telex to "A319/A320?A421 V2500 operators." The telex recommended that, in addition to mandatory compliance wit AD 2003-18-06, operator's consider the following:"… strictly adhere to AMM Task 71-13-00 for proper latching and closing of fan cowl doors after each maintenance action requiring cowl opening…. 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."

The pilot-in-command, first officer, and mechanic were tested for ethanol, basic, acidic, and neutral drugs. All results were normal.

NTSB Probable Cause

The mechanics failure to follow procedures and directives in securing the lower engine cowling after maintenance, and the failure of the first officer to follow the checklist to ensure the engine cowling was secured during the walk around inspection resulting in the separation of the right lower engine cowling during initial take off climb.