APU malfunction at the Gate, MEL procedure

Disclaimer: 

▪︎This content is Not an official document and does not represent the views of Airbus or any other aviation authority.

▪︎The information provided may be incorrect or misinterpreted and should not be relied upon for decision-making. 

▪︎Always refer to official documents and consult with a qualified aviation professional before making any decisions based on the information provided in this blog post.

▪︎The information provided in this blog post is based on personal study and review.

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Ground power unit with Air bridge

 

You are on duty for a turnaround flight. After arriving at the airport gate with an APU restriction, you needed to switch off the APU. When it was time for the next departure and passengers were boarding, you attempted to restart the APU, but it didn't start. In such a situation, there are several factors to consider in order to expedite the departure process.

https://www.isarsoft.com/knowledge-hub/ground-power-unit-gpu

One option might be to use an external air starter unit to initiate the engines' start sequence and follow the Minimum Equipment List (MEL) procedures to continue with the departure. However, the situation became more complex, leading to a delay of over an hour. This complexity arose due to the way the aircraft was connected to ground power.

At some airports, certain air bridges are equipped with a ground electric power supply unit. When an aircraft is connected to such an air bridge, it can receive electricity directly, eliminating the need for a separate ground power unit car. While this capability is convenient in case of APU malfunctions, it presented challenges in your scenario.

Since starting engines with the air bridge connected is not a common procedure, the air bridge needed to be disconnected to initiate engine start at the gate. Subsequently, ground power was provided using a ground power from the air bridge. Electricity had to be temporarily disconnected from the air bridge to establish a connection with the ground power car. This momentary loss of power resulted in a temporary blackout of non-emergency lighting, causing some concern among passengers.

 

 

Applying MEL 

After the pilot switch ground power from air bridge to GPU unit, could the pilot simply apply the MEL, start the engines, and proceed without involving additional paperwork, such as updating the Aircraft Technical Logbook?

airbus safety magazine - recall on the correct use of MEL

 

In accordance with EASA regulations, as mentioned in Airbus safety magazine and Airbus Win document.

when failures or defects occur that cannot be immediately rectified and are covered by an MEL item, the MEL must be applied before departure, subject to the Captain's approval.

he “departure” corresponds to the “commencement of the flight”. “The commencement of the flight” is defined as the moment when the aircraft starts to move under its own power for the purpose of takeoff (i.e. the taxi phase).

 

 

Airbus win - how to manage aircraft system failures that occurs during taxi

 

While I can't distinctly recall the specifics, I vaguely remember that in my previous company's regulations, the window for a pilot to apply the MEL was from after the doors were closed until the request for takeoff power was made.

but these applying window will depend on each company and local regulation. 

 

 

In the current scenario, where the air bridge connection was still established when the APU failed to start, the pilot was technically not authorized to apply the MEL. This was because the aircraft hadn't initiated movement using its own power, a prerequisite for MEL application. Consequently, the pilot had to engage an engineer who could then defer the necessary maintenance action. Subsequently, the engineer would be responsible for updating the aircraft's technical logbook, and we had no choice but to wait for the licensed engineer's assistance.

 

 

 

 

https://safetyfirst.airbus.com/a-recall-on-the-correct-use-of-the-mel/

 

https://www.airbus-win.com/wp-content/uploads/2018/08/00.00.00249-how-to-manage-aircraft-systems-failures-that-occur-during-taxi.pdf

 

 

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Disclaimer:

▪︎This content is Not an official document and does not represent the views of Airbus or any other aviation authority.

▪︎The information provided may be incorrect or misinterpreted and should not be relied upon for decision-making. 

▪︎Always refer to official documents and consult with a qualified aviation professional before making any decisions based on the information provided in this blog post.

▪︎The information provided in this blog post is based on personal study and review.