The cause of the engine failure that resulted in the crash of Dana Air on June 3 may not be determined as the Accident Investigation Bureau in its preliminary report released on Thursday said no data could be recovered from the Flight Data Recorder, a major component of the black box, due to post-crash fire.
The Commissioner, AIB, Captain Muktar Usman, said the digital tape-based memory in the FDR succumbed to the post-crash fire, melted and prevented the recovery of data.
He, however, said that the Cockpit Voice Recorder, which is solid-based, contained 31 minutes of recordings of the last conversation between the flight crew and the control tower.
The report read in part, “The two flight recorders, the Cockpit Voice Recorder and the Flight Data Recorder were analysed at the facilities of the National Transportation Safety Board, Washington, DC, USA.
“The solid state-based memory in the CVR was in good condition and retained 31 minutes of audio information. The digital tape-based memory in the FDR succumbed to the post-crash fire and melted, consequently no data could be recovered.”
Although the AIB boss said investigation was still ongoing, aviation experts doubted if any meaningful information could come out of the final report since the FDR was already destroyed.
The report said the airplane was mostly consumed by post-crash fire, adding that the tail section, both engines and portions of both wings, representing only about 15 per cent of the airplane, were recovered from the accident site for further examination.
The report also said that although preliminary tests conducted on fuel samples were negative, investigators would still conduct further tests on samples of more fuel from the airline.
The report stated, “Fuelling records indicated the airplane was uplifted with 8,000 lbs of fuel before departure from ABV. The flight crew reported to ATC they had 26,000 lbs of total fuel. Preliminary analysis of fuel samples from the refuelling truck and the supply tank at ABV were negative for contamination.
“The investigative activities have included, in part, visual examination of the aircraft wreckage, review of maintenance records and other historical information of the aircraft, documentation of the training and experience of the flight crew, determination the chronology of the flight, review of recorded data, reconstructing the aircraft refuelling, and collection of related fuel samples, and interviews of relevant personnel.
“Future investigative activities will include, but is not limited to, the detailed examination of the engines, further testing of fuel samples, continued factual gathering of relevant historical, operational, maintenance and performance information of the accident airplane in addition to other similar airplane models, further development of the background of the flight crew, further analysis of the CVR audio recording and review of pertinent issues associated with regulatory oversight.”
According to the report, the Captain, Mr. Peter Watxtan, said he lost the second engine of the plane at 15:43, approximately three minutes before it crashed around 15:46.
The report further stated, “At 15:42:35, the flight crew lowered the flaps further and continued with the approach and discussed landing alternatively on runway 18L. At 15:42:45, the Capt reported the runway in sight and instructed the FO to raise the flaps up and four seconds later to raise the landing gear.
“At 15:43:27 hours, the Capt informed the FO ‘we just lost everything, we lost an engine. I lost both engines.’ During the next 25 seconds until the end of the CVR recording, the flight crew was attempting to restart the engines.
“The airplane crashed in a residential area about 5.8 miles north of LOS. The airplane wreckage was on approximately the extended centreline of runway 18R. During the impact sequence, the airplane struck an incomplete building, two trees and three buildings. The wreckage was confined, with the separated tail section and engines located at the beginning of the debris field.”
In the preliminary report, AIB confirmed that the purpose of the ongoing investigation was not to apportion blame, but to prevent such accidents in the future in accordance with the rules of ICAO.
Giving a historical perspective into the crash and the investigation, Usman said, “On June 3, 2012 at about 1545 hours, 5N-RAM, a Boeing MD-83 domestic scheduled commercial flight operated by Dana Airlines Limited as flight 992 (DAN 992), crashed into a densely populated area during a forced landing following a total loss of power in both engines while on approach to the Muhammed Murtala Airport, Lagos.
“Visual meteorological conditions prevailed at the time and the airplane was on an instrument flight plan. All of the 153 persons aboard the airplane, including the six crew members were fatally injured. There were 10 confirmed ground fatalities. The airplane was destroyed. There was post-impact fire. The flight originated at Abuja and the destination was Lagos.
“The airplane was on the fourth flight segment of the day, consisting of two round-trips between Lagos and Abuja. The accident occurred during the return leg of the second trip. DAN 992 was on final approach for runway 18R at Lagos when the crew reported the total loss of power.
“According to interviews, the flight arrived in Abuja as Dana Air flight 993 about 13:50. According to Dana Air ground personnel, routine turnaround activities occurred, including refuelling of the airplane.
“DAN 992 initiated engine start-up at 14.36, taxied to the runway and was later airborne at 14:58 after the flight had reported that it had a fuel endurance of 3.5 hours. Shortly after takeoff, DAN 992 reported 15:45 as the estimated time of arrival at LOS as the flight climbed to a cruise altitude of 26,000 feet. DAN 0992 made contact with Lagos Area Control Centre at 15:18 hours.”
Usman continued, “The cockpit voice recorder retained about 31 minutes of the flight and starts about 15.15 at which time the captain and first officer were in a discussion of a non-normal condition regarding the correlation between the engine throttle setting and an engine power indication.
“However, they did not voice concerns then that the condition would affect the continuation of the flight. The flight crew continued to monitor the condition and became increasingly concerned as the flight transition through the initial descent from cruise altitude at 15:22 and the subsequent approach phase.
“DAN 992 reported passing through 18,100 feet and 7,700 feet, respectively, at 15:30 and 15.40 hours. After receiving a series of heading and altitude assignments from the controller, DAN 992 was issued the final heading to intercept the final approach course for runway 18R.
“During the period of 15:37 and 15:41, the flight crew engaged in pre-landing tasks, including deployment of the slats, and extension of the flaps and landing gear. At 15:41:16 the first officer inquired, ‘Both engines coming up?’ and the captain replied ‘negative.’ The flight crew subsequently discussed and agreed to declare an emergency. At 15:42:10, DANA 992 radioed an emergency distress call indicating ‘dual engine failure … negative response from throttle.’”