Gear-up landing
Following several electrical failures after take-off, the aircraft landed with the landing gear in retracted position.
| Event date : 15 June 2019 | Time : 09:30 UTC |
| Place : Manaus, Brazil | Aircraft : ATR 42-320 |
1. ACCIDENT DESCRIPTION
On June 15, 2019, an ATR-42-320 aircraft, shortly after takeoff from Manaus airport (SBEG) encountered a multiple electrical failure that disabled several instruments and systems. The crew opted for a return to the departure airport, manually flying the aircraft.
Aircraft Flight Path
The landing gear was never extended during the approach, leading to a belly landing on the runway. The aircraft was evacuated using the passenger and service doors. Two passengers suffered from minor injury caused during the aircraft evacuation. The aircraft sustained substantial damage on the lower part of the fuselage.
2. ELECTRICAL FAILURES AND MAINTENANCE OVERSIGHT
2.1 Electrical System Breakdown
The failure originated from DC BUS 2, which lost power due to a malfunctioning Starter-Generator No. 2.
The Bus Tie Contactor (BTC), which should have rerouted power from DC BUS 1, failed to activate.
Due to the loss of DC BUS 2, the Inverter No. 2 ceased to operate. Consequently, through the operation of the AC BTR, the Inverter No.1 took over the supply of the AC BUS 1, AC BUS 2 and AC STBY US.
The Inverter No.1 was found faulty, during the inspection, likely due to load demand higher than normal operation. As a result of this failure, the power supply to the AC BUS 1 may also have been compromised.
Electrical Failure Scenario
2.2 Maintenance findings
The inspections performed after the accident evidenced those findings:
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- On the Starter-Generator No .2: Improper repairs, use of unapproved parts (including the rotor) and metallic dust contamination.
- On the Inverter No.1 : the overvoltage and undervoltage protection settings were incorrectly adjusted with missing diode and short circuit conditions.
- It was not possible to confirm the exact reason of the BTC malfunction. A plausible hypothesis is the non-conformity found in the 58PA relay, which was part of the BTC’s power supply circuit.
Electrical failure scenario
3. LANDING GEAR POWER SUPPLY
The landing gear extension/retraction is powered by the GREEN HYDRAULIC circuit.
On the ATR 42-320, the GREEN HYD PUMP is powered by the DC BUS 2. Hence, in case of the loss this DC BUS 2, the abnormal procedure requires to open the HYD X-FEED to power-up the green circuit with the BLUE PUMP.
DC BUS 2 OFF abnormal procedure for ATR 42-320
4. FLIGHT CREW OPERATION
4.1 Non-adherence to SOPs
The hydraulic cross-feed valve, essential for landing gear extension, was not activated.
Although the BEFORE LANDING checklist was performed, the very short time (less than a second) between the PM reading the item “LDG GEAR – 3 GREENS” and the PF response “DOWN, 3 GREEN”, suggests lack of acknowledgement.
4.2 CRM and Decision-Making Flaws
The Captain remained PF despite SOP guidance to delegate this role during emergencies to provide the Captain with better situational management capabilities.
Throughout the flight, the PM never read the QRH procedures corresponding to the abnormal situation affecting the aircraft, as stipulated in the operator’s SOP.
Communication between crew members demonstrated tunnel vision and low situational awareness.
5. ATR RECOMMANDATIONS
Maintenance Oversight and Compliance
Ensure rigorous oversight of maintenance activities, including those performed by subcontracted repair shops. All maintenance work must strictly adhere to the latest applicable Component Maintenance Manual (CMM) revisions. Regular audits and monitoring are essential to uphold maintenance standards and regulatory compliance.
Unapproved repairs create a risk of unknown flight deck effects for which the flight crew is not trained.
Checklist
Ensure thorough and deliberate verification of each checklist item. Avoid automatic or rote responses. Checklists are designed to confirm the status of critical systems relevant to each flight phase and are essential for maintaining operational safety.
Adherence to SOPs and Effective CRM
Rely on Standard Operating Procedures (SOPs) as they provide structure and task distribution to manage abnormal scenarios effectively. Crew Resource Management (CRM) training should be comprehensive, regularly refreshed, and emphasize clear communication, proper task delegation, and shared situational awareness.
Avoid Premature Landing Decisions
Do not rush to land. Take the necessary time to assess the situation thoroughly and apply the appropriate procedures. A methodical approach enhances safety and decision-making under pressure.
6. FINAL REPORT
The final report in English is available for download at Final investigation report.
