Development of a confined space entry protocol for aircraft fuel systems

Fuel Systems Confined Space Training Program

Worker deaths have been recently noted in confined spaces and 60% of these are deaths of would-be rescuers. The lack of established rescue procedures and the workers' not following technical data provided are among the causes of the fatalities (Millar 1986). With the end-view of addressing the situation, this Manual discusses entry, confined space entry, entry permit, enclosed area, hazards and safe entry. It also contains an emergency response plan and roles, 10 requirements for fuel systems confined space, guidelines for fuel systems safety, and an occupational, physical and respiratory protection program.

Entry, Confined Space Entry, Entry Permit

Entry is any act, which results in any part of an employee's body breaching the plane of the opening of a confined space or enclosed area. It includes any ensuing work in a confined space or enclosed area. Entry into a fuel tank can be in the form of fuel leaks, structural problems, fuel quantity problems, or NDI inspections.

A confined space is one that is large enough for a body to enter, has limited means for entry or exit, and is not designed for continuous occupancy. A confined space must meet all these three conditions in order to be considered a confined space. All aircraft fuel tanks are considered "permit-required" confined spaces, according to T.O 1-1-3. Center-wing dry bay will be tested with 514 Bacharach before entry for inspection or fuel maintenance.

The MXC/CC or his equivalent is responsible for the safe execution of all entries into, and all work performed in, aircraft fuel tanks. The issuance over his or her signature designates the Entry Authority the authorization to issue the Field Permits. The Base bioenvironmental engineers of the Safety and the Fire Department are responsible for evaluating and coordinating work on the Entry Permit Authorization Letter, in addition to those duties outlined by AF Directives. This letter certifies that the Fuel Systems Repair supervisor is empowered to act as the Entry authority for aircraft fuel systems. It is developed by the organization, which supervises the entries and is approved by the MXG/CC. It is issued by the Maintenance Group Commander in coordination with Ground Safety, Base Bioenvironmental engineers and the Fire Department. It authorizes the Entry authority and alternate Entry authority to issue a Field Entry Permit. The Permit must describe the conditions under which maintenance may be performed. It is effective only for a year, certifies the names and positions of the Entry authority and the designated alternates, describes under what conditions the Entry authority will issue the Field Permit, identifies the type of aircraft and the work to be performed, and describes the general atmospheric conditions under which Entry will be made. It also prescribes the type of chemicals, sealants and adhesives, which can be used.

The Field Permit will never be given for entry into a tank possessing an immediate dangerous life health atmosphere. It will ensure that all entries and work to be performed will be according to all safety practices. It will also establish and maintain control over entry into all open fuel tanks. Re-issuance of the Field Permit can be terminated with any change of conditions and a new one must be re-issued when the aircraft is moved or when the confined space is closed, then reopened or when the applicable permit field is filled.

Enclosed Area, Oxygen Deficient Atmosphere, Safe Entry

An enclosed area is a space with limited ingress and egress and which is not large enough to be entered into bodily. In this Manual, enclosed areas are treated in the same way as confined spaces. The center wing dry bay, bottom tank access and top tank access can be considered confined spaces on an aircraft.

One hazard is an oxygen deficient atmosphere. The minimum acceptable oxygen level is 19.5%. At 15-19%, the ability to work strenuously decreases. An impaired condition develops and early symptoms appear. At 12-14% oxygen deficiency, respiration increases and judgment becomes poor. At 10-1%, respiration increases and the lips turn blue. At 8-10%, mental failure occurs, followed by fainting, nausea, unconsciousness and vomiting. At 6-8% level, the condition turns fatal in 8 minutes, 50% fatal in 6 minutes and recovery is possible from 4-5 minutes. At 406%, comma occurs and death in 40 seconds.

Safe Entry. The conditions under which entry is considered safe in a confined space are 10% lower explosion level and oxygen level between 19.5% and 23.5%.

Each section, in coordination with base Medical Services, Fire Department, Safety and Base Bioenvironmental Engineers will develop and write an Emergency Response Plan.

Maintenance Requirements

Before the start of fuel systems maintenance, the shift supervisor insures that the applicable aircraft checklist is accomplished, the required fuel systems equipment are inspected and maintained in serviceable condition, emergency communications established by radio or emergency phones, and the Fire Department of Job Control Department notified of fuel systems maintenance.

Before entering the fuel systems repair area, all non-fuel systems personnel shall check in and get briefed by the fuel systems shift supervisor on the dangers of open tank maintenance. They shall read and sign the fuel systems safety log sheet; remove all watches, rings, lighters, and all spark-producing items, including Goretex clothing.

No other maintenance activity will b conducted in the fuel systems repair area during initial purging operations, bottom draining, depudding and inerting.

A minimum of 2 150-lb Halon fire extinguishers are required for a fuel systems repair area.

Only approved equipment are allowed in the area, such as canvas bags, fiber board, boxes or metal tools. Boxes with rubber rollers will be used to transport tools within the area.

Only authorized explosion-proof lighting materials can be used inside the open fuel tank. Examples are XP65 explosion-proof drop light, Sceon fiber optic lighting system, and explosion-proof flashlights.

Maintenance stands with static discharger plates are accepted if they are made of copper, zinc, or are zinc-coated plates. They are to be bonded to the aircraft, except if they are fuel systems vacuum bowsers, which will then be bonded and grounded (Swift 2000)

No electrical power will be applied to the aircraft during open tank maintenance.

All fuel systems operations will be suspended before lightning strikes within 5 miles of the repair site during bad weather. All fuel systems maintenance are to stop at 30 knots or greater.