A report released by the Accident Investigation Bureau (AIB) has revealed how the poor manufacturer design by Sikorsky Aircraft Corporation caused the Bristow Helicopter Sikorsky S-76C+ with registration number 5N-BGD to crash on August 12, 2015 at the Oworonshoki area of Third Mainland Bridge in Lagos.
The report was one of the four of accidents and serious incidents released on Monday afternoon by the Commissioner of AIB, Engineer Akin Olateru, at the agency’s office at Murtala Muhammed International Airport (MMIA), Lagos. The incidents occurred between July 2004 and August 2015.
The helicopter crashed into Oworonshoki lagoon with 12 persons on board, including two crew members.
There were six fatalities, including the two pilots, while six other persons on board sustained serious injuries.
The helicopter had departed SEDCO Express oil rig at about 14:55hrs and an endurance of one hour and thirty minutes maintaining 3,000ft and was estimated to arrive at Lagos Airport at 15:36hrs, according to the crew information before departure from the rig.
The report stated that the helicopter experienced sudden un-commanded 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 Air Traffic Controllers (ATC), SEDCO Express rig or communicate with the passengers before impact.
AIB in its causal factor of the accident, said “the separation of the Forward Servo Clevis Rod Assembly from the bearing and jam nut (Bell Crack Assembly), which is part of the Cyclic Control System responsible for stabilising the attitude of the helicopter made the aircraft uncontrollable.”
On the contributory factor for the accident, AIB noted that the absence of a secondary mechanical locking system 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 report further stated that the wear was prevalent at the forward servo clevis rod fitting shank, which made the jam nut rotate freely when force is applied.
AIB however gave one safety recommendation on the accident, which was directed to the manufacturer.
He said: “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.”
Olateru stated that AIB was notified of the accident by the Nigerian Civil Aviation Authority (NCAA) at about 16:15 hours on August 12, 2015, while it swiftly dispatched its investigators to the crash site.
He added: “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.”
The other accident report released by AIB was the one involving Pan African Airlines Bell 412 EP Helicopter with registration 5N-BDZ, which occurred near SEDCO Energy Rig Platform on July 26, 2004.
Olateru stated that the erstwhile Accident Investigation and Prevention Bureau (AIPB) received its notification on July 28, 2004, which was 48 hours after the accident. He, however, said the bureau dispatched investigators to the crash site the same day, while all stakeholders were notified.
In the report, the causal factor of the accident could not be conclusively determined, but it was noted that the rostered Pilot in Command (PIC) was not the Pilot Flying (PF). The PF was rostered as the Pilot Monitoring (PM), while the crashed helicopter had a valid Certificate of Airworthiness (COA) at the time of the crash.
In its safety recommendation, like the Bristow Helicopters crash of 2015, AIB issued a sole recommendation of the crash.
Olateru advised NCAA to ensure that heliport operators provide full weather report for operations.
On the serious incident involving an Emirates Boeing 777-200 aircraft with the registration A6-EWD, AIB emphasised that the aircraft had an impact with another B737-400 aircraft belonging to HAK Air with the registration 5N-BOU. The accident occurred at Lagos Airport on July 6, 2015.
According to the report, the Emirates aircraft with 285 passengers had requested to take off through the 18Right runway, which the ATC replied was unavailable at the time, but the pilot opted to use the 18Left runway for take-off.
The report added: “The crew asked for when the runway would be available. The tower reported that the time was not determined, but 18L was available. After determining the aircraft take-off performance, the crew accepted to use runway 18L. The Tower advised UAE782 that taxiing via taxiway C for runway 18L would be at pilot’s discretion due to aircraft wing span.
“However, the crew commenced the taxi and impacted a HAK Air Boeing 737-400 aircraft parked at the parking bay of the General Aviation Terminal (GAT), close to holding point runway 18L, at about 21:38hrs, damaging the rudder and the tail area of the HAK Air aircraft, while the Emirates aircraft sustained damage to its right wing tip.”
AIB made safety recommendations to the Federal Airports Authority of Nigeria (FAAN) and NCAA on the incident.
There was also a report on another serious incident involving Aero Contractors aircraft B737-42C with the registration 5N-BOB, which occurred on the same 18L runway of Lagos Airport on July 21, 2015.
Olateru declared that AIB was notified of the occurrence same day by ATC via phone call, while the bureau immediately dispatched its investigators to the site.
It, however, made two safety recommendations to FAAN and the Nigerian Airspace Management Agency (NAMA) on the incident.