The investigation found two deferred maintenance items (DMI) since December 25, 2020,"
Jakarta (ANTARA) - The National Committee for Transportation Safety (KNKT) presented details of the initial maintenance of Sriwijaya Air flight SJ 182 that crashed into the waters of Seribu Islands on January 9, 2021.

"The investigation found two Deferred Maintenance Items (DMIs) since December 25, 2020," Chief of the KNKT Sub-Committee for Flight Accident Investigation Capt. Nurcahyo Utomo stated during a virtual press conference here on Wednesday.

Maintenance deferral accorded with the flight dispatch rules, he revealed.

Utomo pointed out that the Minimum Equipment List (MEL) pertained to items that should be operational for an aircraft to fly, and any non-operational item can be listed as a Deferred Maintenance Item (DMI).

"On December 25, 2020, the Mach Airspeed Indicator was found damaged on the right side. The maintenance that had been conducted was not successful, and the defect was transferred into the DMI, and the item was classified as repair category C in the deferral list in accordance with the MEL," he stated.

Utomo remarked that items placed in the category C shall be repaired with 10 consecutive calendar days.

"On January 4, 2021, the indicator was replaced, with good result, so the DMI was closed," he revealed.

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On January 3, 2021, the pilot reported that the autothrottle was unserviceable. Autothrottle is a system that enables a pilot to control the power setting of an aircraft's engines by specifying a desired flight characteristic rather than manually controlling the fuel flow. The problem in the autothrottle was later repaired with good result.

The autothrottle reportedly malfunctioned again on January 4, 2021. It was later repaired, though the issue persisted, and it was placed in the DMI list.

The autothrottle was repaired on January 5, 2021, with good result, and the DMI was closed.

"We found no DMI notes in the aircraft maintenance log until January 9, 2021," he stated.

The KNKT found anomalies in the autothrottle system of the Sriwijaya Air flight SJ 182, he remarked.

"Right now, we only know that for the left autothrottle, the retreat was too far. Was it broken? We do not know because both of them moved differently. Both autothrottles of the plane showed anomalies. For the left one, the retreat was too far, while the right one did not move," he explained.

Utomo noted that the movements of an autothrottle were linked to 13 other components.

"Why this anomaly occurred? We must look at the 13 other components related to the autothrottle movement. We have not yet been able to find where is the problem at this moment. We have sent several components, but they have not been able to answer where the problem lies," he stated.

The KNKT had sent several components, including the ground proximity warning system (GPWS), retrieved from the crash site to the aircraft's manufacture. (INE)

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Translator: Juwita Trisna Rahayu/Suharto
Editor: Yuni Arisandy Sinaga
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