ASN Wikibase Occurrence # 244881
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| Date: | Thursday 12 November 2020 |
| Time: | 20:55 UTC |
| Type: |  Britten-Norman BN-2T-4S Defender 4000 |
| Owner/operator: | Police Service of Northern Ireland (PSNI) |
| Registration: | G-CGTC |
| MSN: | 4019 |
| Year of manufacture: | 2013 |
| Engine model: | Rolls Royce M250-B17F/1 |
| Fatalities: | Fatalities: 0 / Occupants: 3 |
| Aircraft damage: | None |
| Category: | Incident |
| Location: | over Limavady, County Londonderry -
 United Kingdom
|
| Phase: | Manoeuvring (airshow, firefighting, ag.ops.) |
| Nature: | Aerial patrol |
| Departure airport: | Belfast International Airport (BFS/EGAA) |
| Belfast International Airport (BFS/EGAA) | |
| Investigating agency: | AAIB |
| Confidence Rating: |  Accident investigation report completed and information captured |
The AAIB final report was published on 16 September 2021:
"The aircraft, a BN2T-4S Islander, suffered a double engine failure, likely due to intake icing, while operating in IMC at approximately 7,000 ft amsl.
The plan of the flight was to depart Belfast Aldergrove Airport and route to an operating area, climbing to an altitude of approximately 10,000 ft amsl. The crew consisted of the pilot and two observer passengers. Before flight the crew conducted a briefing in which the meteorological information was an area of particular concern as a cold front was approaching the operating area bringing extensive cloud and reducing temperatures. The pilot was conscious of the risks of airframe icing and during the brief decided to operate the aircraft below the 0°C isotherm.
The aircraft taxied at approximately 19:50 hrs for departure from runway 17 at Aldergrove. While taxiing, the aircraft was given a different ad hoc task. The pilot informed ATC of the change and arranged a new departure clearance. Shortly afterwards the pilot was told by one of the observers that the new task had been resolved and therefore the aircraft was to revert to its original plan. The pilot requested an appropriate departure clearance, but the aircraft was then required for the ad hoc tasking once again. The pilot again requested a change of departure clearance and stated he felt somewhat exasperated by the frequently changing situation.
The aircraft took off from runway 17 at 20:05 hrs and routed to the new operating area. This tasking was at lower levels, so the pilot climbed to approximately 1,600 to 1,800 ft amsl. The lower altitude allowed the aircraft to operate clear of cloud, and icing conditions were not an issue. The task was concluded at 20:25 hrs and the aircraft was released to continue with the originally planned operation. The pilot set course for the operating area and requested clearance to operate up to FL 090.
During the transit the pilot decided to stop the climb at approximately 7,000 ft amsl to remain below the 0°C isotherm. At 7,000 ft he recalled that the air temperature was +1°C. During the transit the aircraft entered cloud and as it did so the pilot recalled selecting the engine anti-icing on. The aircraft reached its operating area at approximately 20:45 hrs. After around five minutes on task the pilot noticed that the torque indications for both propellers were reducing, with a related decrease in airspeed. He therefore increased power to restore both torque and airspeed. A short time later the pilot again noticed a drop in both torque and airspeed. The aircraft needed "more and more power" to maintain the required performance and the pilot became concerned that something was amiss. He then noticed that the turbine gas temperature (TGT) on both engines had reached the limit of 927°C.
At this point the pilot reduced power to keep the TGT within limits. He informed the rest of the crew that there was a technical issue with the aircraft and that his intention was to return to Aldergrove. The pilot recalled that during the subsequent left turn the right engine failed, stating, "I was so startled I did not do any immediate drills but concentrated on maintaining control of the aircraft." Given the already evident engine issues he was now concerned that the second engine would also fail. He recalled that as he thought this, the left engine failed.
The pilot was aware of the aircraft’s position and decided that his only option was to try to glide to the nearer City of Derry Airport, Eglinton. He established the aircraft in a glide and then completed the engine shutdown and propeller feathering drills. He declared mayday to Aldergrove ATC and asked for vectors toward Eglinton. He was aware that Eglinton was closed so asked Aldergrove ATC if they could do anything to get the airfield lighting switched on.
The aircraft’s topographical moving map display is role equipment and requires electrical supply from the generators and so was lost when the engines stopped. The pilot had an iPad with a mapping application but this also was not working. The observers also had iPads with mapping applications and one of them went to the cockpit to assist.
During the descent the pilot attempted to restart the engines and 1 minute 30 secs after the second engine failure he was able to restart the right engine at approximately 2,100 ft amsl.
The aircraft had cleared cloud and the pilot could now see nearby cultural lighting. From the observer’s iPad he could see the aircraft was over Loch Foyle. At approximately 1,500 ft amsl he then attempted a restart of the left engine. The first attempt was unsuccessful, which he attributed to not having selected the left engine igniters on. On what he recalled was the second attempt the left engine also restarted.
The pilot decided to continue to land at Eglinton. Using the iPad map, and with the observer assisting with navigation, he flew the aircraft towards the airport. The pilot recalled that the wet runway surface at Eglinton became visible in reflected cultural lighting as the aircraft flew overhead at approximately 900 ft agl.
Considering that this was too high for a safe approach he flew a left hand circuit to reposition on the centreline for runway 26. The aircraft descended during the circuit and the pilot recalled seeing the runway from a height of approximately 350 ft agl. He then made a powered landing on the unlit runway. After landing the pilot taxied the aircraft to the main parking area and completed the shutdown checks. All on board were uninjured.
=AAIB Conclusion=
It is likely the engine anti-icing system was not selected on before entry into cloud with an outside air temperature less than 5°C. A build-up of ice in the engine ducts probably caused the engine symptoms noted by the pilot and the subsequent rollbacks and flameouts. The investigation found that the pilot’s limited recent experience in icing conditions was likely to have been a contributory factor, and that circumstances causing stress and fatigue could have affected his performance. Both engines were relit during the descent and a safe landing was made at Eglinton, although the airport was closed."
Accident investigation:
 |
|
Sources:
1. AAIB Final Report: https://assets.publishing.service.gov.uk/media/612f8ea18fa8f50327b49b6f/BN2T-4S_Islander_G-CGTC_10-21.pdf
2. https://news.causewaycoastcommunity.co.uk/local-news/aircraft-from-psni-air-support-unit-makes-emergency-landing-at-city-of-derry-airport/
3. https://www.bbc.co.uk/news/uk-northern-ireland-foyle-west-54924746
4. https://www.belfasttelegraph.co.uk/news/northern-ireland/psni-plane-makes-emergency-landing-during-co-derry-security-alert-39744269.html
5. https://www.newsletter.co.uk/news/crime/psni-plane-makes-emergency-landing-after-engine-failure-3035476
6. https://en.wikipedia.org/wiki/Limavady
Media:
A BN2T-4S Islander (G-CTGC) suffered a double engine failure, likely due to intake icing,12 November 2020, City of Derry Airport, Eglinton.
— AAIB (@aaibgovuk) September 16, 2021
Read the report: https://t.co/XqhEsMqe45 pic.twitter.com/ZsbhkvWRpE
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 13-Nov-2020 19:51 | ryan | Added |
| 14-Nov-2020 08:42 | Aerossurance | Updated [Operator, Location, Phase, Nature, Source, Narrative] |
| 14-Nov-2020 08:45 | Aerossurance | Updated [Narrative] |
| 18-Nov-2020 15:03 | loadmaster | Updated [Registration] |
| 27-Feb-2021 18:38 | rudy | Updated [[Registration]] |
| 16-Sep-2021 09:40 | harro | Updated [Time, Aircraft type, Cn, Total occupants, Other fatalities, Source, Narrative, Accident report] |
| 16-Sep-2021 09:48 | harro | Updated [Aircraft type] |
| 27-Sep-2021 22:37 | Dr. John Smith | Updated [Source, Embed code, Narrative, Category] |
| 17-Apr-2022 16:38 | Aerossurance | Updated [Nature, Embed code, Narrative] |
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