Investigators call for modifications after aircraft crashed into sea when engines failed
Investigators are recommending modifications to ATR fuel-quantity indicators after discovering that the Tuninter ATR 72 lost in a fatal accident off Sicily in August was fitted with an indicator intended for ATR 42s.
Wreckage from the aircraft, which ditched off Palermo on 6 August after a dual engine failure, reveals that an incorrect fuel gauge was installed. The gauge could have erroneously shown that the ATR 72 was carrying at least 1,800kg (4,000lb) more fuel than it actually had.
Investigation body Agenzia Nazionale per la Sicurezza del Volo (ANSV) has issued two emergency recommendations to the European Aviation Safety Agency (EASA). One urges operators to carry out checks to ensure their ATRs have the correct fuel gauges.
The second suggests that the gauges should be modified to make it impossible to fit the wrong one to either aircraft type.
At present, says the ANSV, “the only visible difference between the two fuel quantity indicators [FQI] is in a small notice in white script indicating the maximum quantity of fuel per wing tank, situated on the face of the instrument”.
Mounted on the captain’s side of the instrument panel, the gauge displays the fuel quantity in the ATR’s two wing tanks. The ANSV says the ATR 42 gauge, if fitted to an ATR 72, would incorrectly show a fuel level “greater than that actually present”, with the error “not less than 900kg per fuel tank”.
A fuel load of just 600kg on an ATR 72 would have registered on the ATR 42 display as 2,750kg. If the ATR 72’s tanks were empty, a wrongly-fitted fuel gauge would indicate that the aircraft was still carrying 1,800kg.
In an all-operators bulletin, ATR says the evidence points to “inappropriate” fuel gauge installation. It says the manner in which the central fuselage and wings floated after the crash, plus the lack of fuel traces, support a fuel-exhaustion scenario. The ANSV made a similar observation to explain the priorities in the early part of its investigation, which it says is still continuing “with the aim of verifying all the factors which contributed in various ways” to the accident cause.
Tuninter flight 1153 had been 45min into a Bari-Djerba crossing, cruising at 23,000ft (7,000m) with 39 people on board, when the aircraft’s right-hand engine failed. The crew opted to divert to Palermo but “3-4min later, as the aircraft was descending through about 7,000ft, the left-hand engine also failed”, says the ANSV.
The aircraft glided for about 16min before crashing 23nm (43km) north-east of Palermo airport. “On impact with the surface of the sea, the aircraft broke into three sections,” says the ANSV. Fifteen passengers and one of the cabin crew were killed.