In an extremely rare incident, an Air Baltic A220 aircraft (erstwhile Bombardier CS-300) suffered a dual engine shut down event , while it made an attempt to land at Copenhagen,Denmark.
The incident aircraft registered as YL-AAQ comes installed with two PW1524G engines, a variant of the Pratt & Whitney PW1000G high-bypass Geared Turbo Fan (GTF) engine family.
On 11th of July , the aircraft was carrying out a flight BT-139 from Riga - Latvia (RIX) to Copenhagen-Denmark (CPH), without any apparent issues throughout the flight.
While making an attempt to land on Copenhagen's runway 04L, both the GTF engines shut down automatically on touch down, with out any physical damage to the aircraft or injuiries to the occupants .
Though both the engines were out, cockpit crew could manage the control of the aircraft with a high speed taxi- out of the Runway. On stoppage of the aircraft, it was further towed away to a remote bay.
Though nothing is revealed yet regarding the dual engine shut down and we have to wait till investigation over , there are some speculations on this uncommanded shutdown.
May it be a result of certain logical command from the engine FADEC (Full Authority Digital Electronic Control) under the influence of an unknown malfunction !
One thing interesting comes out of this incident is, engines did not shut down during the flight, but on touch down, which indicates , there is something or some logic to do with the WOW (Weight On Wheel) sensor command.
Though, WOW condition will not command a direct engine shut down, certain engine sensor signal lost logic or other malfunction such ie, speed sensors or N1 exceedance logic along with ground conditions (WOW signal) might have caused such dual shut down, as speculated.
Some sources also suggest, In case of the PW GTF engines, there exists a TCM logic which in case of a a thrust control malfunction, will shut down the engines on ground if the thrust levers are at idle or in reverse position.
Earlier there were cases of Airbus A220 aircraft Inflight engine shut down [IFSD] due to water ingress into Fwd avionics compartment !
Transport Canada had to issue an Airworthiness directive No# CF-2020-30 to addrees the IFSD issue with Airbus A220 [ erstwhile Bombardier CSeries ] aircrafts .
Description :
AD describes , following an in-service engine shutdown during taxi, it was discovered that water was dripping into the forward avionics bay. The water had caused a short circuit, tripping a circuit breaker that led to the engine shutdown.
Cause :
The source of the water was rain entering through the main cabin entry door while it was open, causing the drains to overflow and dripping on the forward avionics bay below.
The research :
Water ingress into the forward avionics bay could short circuit the equipment in the area and lead to a loss of air data sources resulting in a reduction in functional capabilities, and an increase in crew workload .
The Fix /Preventive action :
AD requires a modification to install blanking plates on certain drains, and block off the associated drain tubing to prevent any future water ingress from the forward galley drains into the forward avionics bay.
