Africa's Connection D228 at Sao Tome on Dec 18th 2018, nose gear did not extend
Last Update: December 13, 2020 / 19:17:05 GMT/Zulu time
Incident Facts
Date of incident
Dec 18, 2018
Classification
Accident
Airline
Africa's Connection
Departure
Sao Tome, São Tomé and Principe
Destination
Douala, Cameroon
Aircraft Registration
S9-AUN
Aircraft Type
DORNIER 228
ICAO Type Designator
D228
On Mar 14th 2019 Germany's BFU reported in their December Bulletin that the aircraft was on approach to its destination when the crew found the nose gear coul not be lowered and returned to their point of origin, where the aircraft landed with retracted nose gear. The occurrence was rated an accident, the BFU representing the state of aircraft design is supporting the investigation according to ICAO Annex 13.
In December 2018 Africa's Connection is said to have operated three Do-228 aircraft, however, only two tail numbers are known: S9-RAS and S9-AUN (only these two aircraft are on the Sao Tome Aircraft register). A local paper claimed the accident aircraft carried an Ukrainian tail number, however, Ukraine has no Do-228 on its aircraft register (editorial note: it is possible there is some confusion with UR-CKC, see Accident: Cavok AN74 at Sao Tome on Jul 29th 2017, rejected takeoff due to flock of birds results in runway overrun as local media mixed coverage of both occurrences). The airline themselves state they operate 2 Do-228 and one Hawker Jet. The paint scheme supports S9-AUN being the accident aircraft, a photo in social media showing the aircraft still sitting at the runway threshold 29 the following morning confirms S9-AUN to be accident aircraft.
Sao Tome and Principe's National Civil Aviation Authority (INAC) released their final report concluding the probable causes of the accident were:
During towing of the aircraft, the pin for towing came out and at time of turning it damaged the nose landing gear torque link affecting the alignment and centering of the nose wheel.
After take off and selecting landing gear up, the nose gear was stuck in the nose compartment due to 15º off deflection from centre point.
Nose wheel could not be extended because it was stuck in the nose compartment.
Contributory Factors
The contributory factors to this accident include but are not limited to the following:
- Inadequate tow bar.
- Inadequate aircraft tow tractor.
- Aircraft tow tractor was technically faulty.
- Lack of appropriate training for ground personnel on aircraft towing.
- Undocumented ground personnel discharging maintenance duties.
- Roughness and degradation of taxiway surface.
- No action was taken for specific inspection on the nose landing gear for any damage caused during towing the aircraft.
- No compliance with Service Bulletin nº SI-228-036 issued by the manufacturer on 28th April 1989.
The INAC summarized the sequence of events:
At 14h16 UTC the aircraft DO 228, S9-AUN departed from São Tomé to Douala with estimating flight time of 01h42.
After take off the crew noticed that with gear retracted the transition light did not go off and was on throughout the flight.
At destination and during the approach for landing, selecting landing gear down, the crew realized that the nose gear was not down and only main gear was extended and locked. The crew performed the troubleshooting to identify the cause and recycled the landing gear but to no avail. The situation prevailed with nose gear up and main gear extended and locked.
In this regard and due to inability to land safely in Douala, the crew decided to return to home base at São Tomé Airport.
During the remaining flight back home the crew established normal communications with Libreville Control and later on with São Tomé ATC, but at no time the crew reported to São Tomé Air Traffic Control (ATC) for any emergency situation despite they had requested the Air Traffic Controller to inform the Company‘s Flight Operations Office that they were having a technical problem.
At 17h39 the crew requested for visual approach and ATC cleared the aircraft to visual approach and to report base leg of runway 11.
At 17h43 on final approach and when cleared to land the crew informed that they could not land due to nose gear malfunction and performed the go-around procedure. There after they did a low pass and Air Traffic Controller confirmed the nose gear was not down. At 17h44 the crew declared emergency.
The Air Traffic Controller immediately informed the Airport Fire Service and other related specialized services and authorities. All emergency procedures on ground were observed including applying foam on the runway to soft and mitigate the damage of the aircraft and preventing any fire situation.
At last the aircraft was able to perform an emergency landing only with main gear extended at 18h53 UTC, without injuries and fatalities. The aircraft was partially damaged.
The INAC analysed:
General
After daily inspection and before departure the aircraft is towed between fuel pit hangars to main ramp. These have been the routine by the maintenance technician and other ground personnel whenever there is flight to be operated. The taxiway is not in the good shape because of roughness and degradation of the surface what should be the reason for maintenance ground personnel to have more appropriate and careful handling during aircraft towing. There are evidence that the pin have come out a couple of times without company’s maintenance to take any corrective action to address the issue.
On the day of occurrence when the pin came out and during turning it affected the nose landing gear torque link that suffered serious damages. No action whatsoever was taken to correct the situation.
It is pertinent to emphasize that the manufacturer issued a service bulletin on 28 April 1989 to improve safety pin on Nose Landing Gear (for towing). If the modification according to that service bulletin was effectively complied it could avoid the pin to come out even with strong vibration due to taxiway roughness.
On the day of the flight the crew filed a flight plan from São Tomé to Douala contrary to previous Civil Aviation clearance indicating Yaoundé as first destination. There was no evidence available to CNIPAIA to ascertain the reasons for change of the destination.
Conduct of flight
The aircraft took off at 14h16 with estimating time flight of 01h42 to destination.
Given the situation that after departure the landing gear transition light did not go out with gear up, the investigation could not establish the reason that made the crew to continue the flight in that condition.
During approach for landing at Douala, the crew realized that the nose gear was not down and only main gear was extended and locked. In keeping with procedures laid down in emergency checklist the crew performed the troubleshooting to identify the cause followed by recycling the landing gear. During the recycling the main landing gear did not go up while the nose gear maintained always up. In face of that the crew returned back to São Tomé flying with main gear down on emergency condition.
It is pertinent to note that the crew neither reported to Libreville ATC nor reported to São Tomé ATC any emergency or landing gear malfunction.
On final approach and when cleared to land the crew informed that they could not land due to nose gear malfunction and performed the go-around procedure. There after they did a low pass and Air Traffic Controller confirmed the nose gear was not down. Only at that time the crew declared emergency.
The crew performed a professional emergency landing with only main gear extended. There were no injuries and fatalities.
The weather situation was good all day in the area making flying less stressful for the crew specially taking in account the emergency landing to be performed.
License issues
Aircraft Maintenance Technician (AMT) Licence was expired on 10 August 2018.
Assistant Mechanic Aircraft Maintenance Certificate was expired on 16 March 2015.
It is not understandable how the technicians were discharging its duties with expired licence and certificate and having also an undocumented ground staff as part of the team.
Incident Facts
Date of incident
Dec 18, 2018
Classification
Accident
Airline
Africa's Connection
Departure
Sao Tome, São Tomé and Principe
Destination
Douala, Cameroon
Aircraft Registration
S9-AUN
Aircraft Type
DORNIER 228
ICAO Type Designator
D228
This article is published under license from Avherald.com. © of text by Avherald.com.
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