Considerations Related to Human Factors in Aircraft Fuel Tank Systems

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A large percentage of the work involved in performing inspection and modification of aircraft fuel tanks and their systems is typically carried out with the fuel tank itself. Such tasks require maintenance personnel to physically enter the tank, where significant environmental hazards exist.

Fuel Tank related work is one of the most difficult challenges an aircraft maintenance worker may face. Not only the challenge of physical entry and moving around within the tank, the additional challenge of multiple hazards including health and safety hazards, most notably oxygen deficiency, flammability, explosion and the toxic effects of fuel vapours.

The Challenges Associated With Fuel Tank Entry

Aircraft Fuel Tanks are a significant source of Hazards and it is important that we are able to assess the risk and to develop appropriate mitigations. Potential hazards include the possibility of fire and explosion, in addition kerosene is both toxic and irritating. Perhaps the biggest potential threat is oxygen deficiency.

The physical construction of the fuel tank creates a significant hazard due to the confined nature of the fuel tank. Moving to the rear of a tank internally can be a slow & arduous process.

A significant amount of fuel tank inspection work off course takes place within tank environment which means that inspection and maintenance personnel must physically enter the fuel tank

This creates a challenge for the organisation to manage both the process and the exposure to environmental hazards, where many environmental hazards exist.

The Maintenance Repair Organisation (MRO) should develop specific procedures to:

a) Identify all direct and indirect hazards associated with fuel tank entry

b) Introduce appropriate controls to either eliminate or mitigate the identified hazards

Taking Precautions

MRO’s need to develop manage and provide training of safety procedures for fuel-tank entry personnel.

The following elements should be considered as essential content when considering the need for safety procedures.

a) A detailed list of Fuel-tank entry and other related work hazards.

b) Appropriate Preparation of the Fuel Tank to support entry (including Fuel Tank Venting Procedures

c) Conditions required for entry (including the necessary support equipment – communications – breathing etc)

d) Emergency response plan, considering all possible eventualities including medical and developing appropriate actions.

Training for Confined Spaces

To meet occupational health & safety obligations employees require training prior to their first entry within a confined space. Typically, the authorisation or “permit” will be valid for a period of 12 months.

Records of such training should be maintained and retained in accordance with local requirements.

Sofema Aviation Services and our sister online training portal Sofema Online offer both classroom and online (with voice over) training compliant with the requirements of both EASA and FAA SFAR 88. For details please see our websites or email or

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