Maintenance Oversight Leads to Cockpit Smoke on Embraer Flight

Casualties unknown • Abeam Potchefstroom during the climb phase whilst passing flight level 245, ZA

A scheduled passenger flight experienced cockpit smoke due to an uninspected recirculation fan, forcing an emergency return to O.R. Tambo International.

What happened

On the afternoon of 22 August 2024, an EmbraER ERJ-135LR, registration ZS-OUV, was operating a scheduled passenger service from O.R. Tambo International Aerodrome (FAOR) to Sishen Airport (FASS). While the aircraft was climbing through 24,500 feet near Potchefstroom, the flight crew detected a burning odor in the cockpit, followed shortly by white smoke emerging from a louver vent.

Following established safety protocols, the crew donned oxygen masks and consulted the Quick Reference Handbook (QRH). After verifying that the cabin remained clear of smoke, the crew deactivated the aircraft's recirculation fan, which successfully dissipated the smoke. The first officer subsequently declared a "PAN PAN" emergency, and the captain returned the aircraft to FAOR. The flight landed safely approximately 51 minutes after departure, with no injuries reported to the 14 passengers or the three crew members.

The investigation

An investigation by the SACAA AIID focused on the mechanical failure of the number one recirculation fan. Investigators examined the maintenance history of the component and found that the fan had significantly exceeded its recommended service interval. While the manufacturer requires an inspection of the fan every 5,000 hours, the component had reached 12,619.08 hours before the failure occurred.

During the most recent C-check, the fan had already accumulated 9,330.5 hours, meaning the required 5,000-hour inspection had been missed. The investigation confirmed that the aircraft was released for service despite this oversight.

Findings

  • The smoke in the cockpit was caused by the scorching of the recirculation fan's driver card, control board, and power board.
  • The fan's internal components, specifically the ball bearings, were found to be worn and loose.
  • Significant dirt contamination was present within the fan assembly.
  • The primary cause of the smoke was the lack of required maintenance on the recirculation fan.
  • The failure to adhere to the manufacturer's recommended maintenance schedule allowed the component to operate well beyond its inspection limit.

Probable cause

The cockpit smoke originated from the electrical failure and scorching of the number one recirculation fan's control and power boards, driven by worn bearings and dirt accumulation resulting from a failure to perform required maintenance inspections.

Frequently asked questions

What happened in the 2024-08-22 Embraer ERJ-135LR accident near Abeam Potchefstroom during the climb phase whilst passing flight level 245, ZA?

A scheduled passenger flight experienced cockpit smoke due to an uninspected recirculation fan, forcing an emergency return to O.R. Tambo International.

What aircraft was involved and where did it happen?

The accident on 2024-08-22 involved a Embraer ERJ-135LR, registration ZS-OUV, at Abeam Potchefstroom during the climb phase whilst passing flight level 245, ZA.

What was the probable cause of the accident?

The cockpit smoke originated from the electrical failure and scorching of the number one recirculation fan's control and power boards, driven by worn bearings and dirt accumulation resulting from a failure to perform required maintenance inspections.

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