Airbus has enhanced operational documentation to provide greater clarity on engine-relight procedures after severe hail extinguished both powerplants on a LATAM A320 two years ago.
Such was the storm’s intensity that it “significantly exceeded” engine design and certification criteria, according to the airframer, with water and ice content twice the certified level.
The aircraft encountered the storm while flying to Asuncion from Foz do Iguacu in Brazil – to where it had initially diverted due to weather conditions – on 26 October 2022.
After departing Foz do Iguacu, which lies east of Asuncion, the crew attempted to avoid adverse weather by flying northwest, before turning south towards the destination.
The jet had been cruising at 24,000ft, with autopilot and autothrust engaged, when it carried out a left turn and flew into the hailstorm shortly afterwards.
“Loud impact noises were heard, and both the left and right windscreen sustained damage,” says a case study on the event in Airbus’s latest Safety First publication.
It says the autopilot and autothrust disengaged, the cockpit “went dark”, and several alert messages were issued including those for engine systems and windshield anti-ice.
Reversion to an emergency electrical configuration meant the subsequent 2min 46s of flight-recorder data was lost.
But the case study says that, while the thrust levers were advanced to go-around power, both engines had flamed out and the aircraft was alerting the crew to unreliable airspeed.
The pilots’ activation of the auxiliary power unit restored electrical power.
At this point the aircraft had lost nearly 6,000ft of altitude, and was operating in alternate flight-control law, with its thrust levers still at go-around setting.
One attempt to relight the right-hand engine by windmilling was recorded – the jet was pitched 3.5° nose-down, to assist with this effort – before the crew tried several times to use starter-assisted engine relight, with both engine master switches simultaneously on.
The crew eventually retarded the thrust levers to idle before successfully relighting the left-hand engine, with the right-hand engine master switch left off.
It had lost almost 15,000ft in altitude, descending to 9,100ft, by the time the engine was relit. The crew twice tried to relight the right-hand powerplant but neither attempt was successful.
Despite the loss of power, windshield damage, and degraded control laws, the crew conducted a safe single-engine approach – in darkness – to Asuncion, 26min after the flame-out. The jet was found to have lost much of its radome during the occurrence, causing disruption to airflow and resulting in the loss of reliable airspeed and reversion to alternate law.
The aircraft (CC-BAZ) was fitted with CFM International CFM56 powerplants.
While a windmilling restart can be attempted on both engines simultaneously, says the Airbus case study, starter-assisted relight is only available below 20,000ft.
It adds that the crew’s attempt to use starter-assisted relight on both engines simultaneously had failed because the APU bleed provides sufficient air pressure to restart only one engine at a time.
Only after the crew concentrated on the left-hand engine, turning the right-hand engine master switch off, was enough bleed pressure provided to the left-hand starter for a relight – some 8min 26s after the flame-out. The right-hand engine could not be restarted because it had sustained too much damage during the event.
Airbus says the event prompted it to improve operational documentation, across its aircraft range, to “prevent misinterpretation” of starter-assisted relight. The improved procedure highlights that the process should be applied to just one engine at a time.
Careful application of procedures after all-engine flame-out is “critical”, the case study says, especially given that the situation is “high stress” and successful resolution demands “meticulous execution”.
This includes maintaining optimum relight speed for windmilling attempts, ventilating combustion chambers, and setting idle thrust to avoid a possible stall from immediate acceleration if engine power is restored.
Airbus adds that it is planning a relevant update to the flight warning system on its widebody A350 and A380 models, to improve electronic centralised aircraft monitor procedures, in 2026.
