Implementation of AIB safety recommendations reducing air crashes
By Lawani Mikairu
The recent swift implementation of the safety recommendations of the Nigeria Accident Investigation Bureau, AIB, on the Bristow Helicopter crash that occurred in Lagos on 12th August, 2015 by the makers of the Sikorsky S-76C+ helicopter with registration no 5N-BGD, has helped in reducing the rate of air accidents involving the helicopter type.
One of the mission statements of AIB that,” Accident Investigation is a strong pillar of safety in the aviation industry and making the report available timely is as critical as Accident Investigation itself. The purpose of accident investigation, however, is not to apportion blame or liability but to prevent future recurrence of similar incidents’ cannot be more critical now in Nigeria aviation industry.
Since its inception in 2007, AIB has issued 39 Final Reports and made 154 Safety Recommendations. These Safety Recommendations have impacted air safety positively not only in Nigeria, but globally. The bureau recently released 4 Final Reports, including 7 Safety Recommendations and the Bristow Helicopters Sikorsky S-76C+ helicopter crash in Lagos was one of the four reports.
According to AIB, the bureau was notified of the Bristow Helicopters air accident by the Nigerian Civil Aviation Authority ,NCAA, at “about 16:15hrs on 12th of August, 2015. Investigators were dispatched to Oworonsoki area of Lagos immediately. All relevant authorities were notified”.
“5N-BGD departed SEDCO Express oil rig at about 14:55hrs on 12th August, 2015 with 12 persons on board including two crew members and an endurance of one hour and thirty minutes maintaining 3,000ft. The estimated arrival at Murtala Muhammed Airport (DNMM), Lagos was 15:36hrs according to the crew information before departure from the rig”.
“At about 15:31hrs, the 5N-BGD, Sikorsky S-76C+, crashed into the Lagoon at Oworonsoki area of Lagos. Visual meteorological conditions prevailed at the time and a VFR flight plan was filed. The helicopter experienced sudden uncommanded pitch up, yaw, and roll for about 12 seconds until it impacted water at about 15:31hrs. The pilots were neither able to make any form of distress call to ATC, SEDCO Express rig nor communicate with the passengers before impact”.
“Rescue Operation was swift, prompt and carried out by local fishermen who were in the area. There were six fatalities, including two crew members and six seriously injured passengers. The crew members were recovered the following day. The helicopter was destroyed but there was no post-impact fire”.
AIB findings on the crash showed that the, “ Causal Factor was the separation of the Forward Servo Clevis Rod Assembly from the bearing and Jam nut (Bell Crank Assembly) which is part of the Cyclic Control System responsible for stabilizing the attitude of the helicopter made the aircraft uncontrollable”.
And the “Contributory Factor was the absence of a secondary mechanical locking system (lock-pin or wire-lock) in the design of the Forward Servo Input Control Rod assembly contributed to the separation of the Forward Servo Clevis Rod from the bearing and Jam nut. The wear that was prevalent at the Forward Servo Clevis Rod end fitting shank, which made the Jam nut rotate freely when force is applied”.
One of the Safety Recommendations made by AIB is that: “Sikorsky Aircraft Corporation should redesign the affected control pushrod assembly by introducing wire lock or lock pins as safety features between the Jam nut and the Pushrod to enhance better security and safety”.
This major design recommendation has been swiftly implemented by Sikorsky Corporation, and this has made the redesigned Sikorsky S-76C+ helicopters one of the safest choppers currently flying around the globe.
The Nigeria Civil Aviation Authority, NCAA, can do the civil aviation industry a lot of good by insisting on prompt implementation of AIB safety recommendations involving Nigeria aviation agencies, airline operators and stakeholders. There are many recommendations yet to be implemented.