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Universal Fault Interrupter (UFI) Application: Center Tank Override Pump Auto Shutoff with Ground & Arc Fault Protection. UFI Technology Fuel System Protection. Relay sized, microprocessor based monitoring device adaptable to control center tank override pumps on B737, B757, B767, & B747

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UFI Technology Fuel System Protection

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Ufi technology fuel system protection

Universal Fault Interrupter (UFI) Application: Center Tank Override Pump Auto Shutoff with Ground & Arc Fault Protection


Ufi technology fuel system protection

UFI Technology

Fuel System Protection

  • Relay sized, microprocessor based monitoring device adaptable to control center tank override pumps on B737, B757, B767, & B747

  • Provides pump dry-run protection within FAA specified 15 second window

  • Comprehensive electrical fault protection

    • Line-to-Line

    • Line-to-Ground

    • Intermittent opens (wires, connectors)

    • Phase imbalance

  • Other out-of-range conditions such as locked rotor, & bearing wear

  • Downloadable history database

  • No scheduled maintenance


Ufi technology system features

UFI TechnologySystem Features

  • Fully certified to meet Amendment 25-102 without exceptions

    • UFI Hardware DO-254, Software DO-178B, Both to assurance level B

  • Satisfies two of three SFAR 88 regulatory requirements

  • Passive monitoring – can not introduce electrical signals into fuel tank wiring

    • Actively controls fuel pump relay

  • Reliability greater than existing system components, MTBF >100K hours (calc)

  • Non-intrusive installation, piggy-back or close proximity to existing pump relay

  • Transparent operation, crew reset-able

  • Technology adaptable to any 3-phase synchronous pump motor


Ufi technology development status

UFI TechnologyDevelopment Status

  • FAA Certified December 2005 to Amendment 25- 102, latest fuel tank safety requirements, granted STC # ST01844LA (Boeing 737-300)

  • Installation development and certification for B757, B737NG, & B767 in work.

    • Remote mounting and universal voltage adapter (RAM) added to accommodate any relay or panel space configuration

  • Expansion capability:

    • Adaptable to meet future regulatory requirements resulting from SFAR 88


Ufi technology how stuff works

UFI Technology‘How Stuff Works’

  • The UFI is a micro computer device which monitors the three phase wiring to the center tank pumps.

  • The UFI is an in-the-loop device between the cockpit switch and the pump control relay.

  • Each time the pump switch is energized the UFI checks for pump and wiring fault conditions.

  • Any time the UFI detects a fault condition it will remove power to the pump relay.

  • The cockpit crew will be alerted to the fault by a ‘pump pressure low’ indication.

  • Two UFI’s are required for complete center tank protection.

    • One for each pump relay.


Ufi technology fuel system protection

UFI Technology - Block Segmentation

Unique to “microcontroller” detection path

Unique to “hardware” detection path

Common to both detection paths

Common circuits and Relay Control (FET)


Ufi technology fuel system protection

UFI Technology

Example of Run-Dry Electrical Signature

Current Trace of Fuel Pump Dry-Run Condition


Ufi technology fuel system protection

UFI Technology

Example of Run-Dry Electrical Signature, (event continued)

Last current surge above predetermined threshold.

Dry-Run Delay

Power Removal

Current Trace of Fuel Pump Dry-Run Condition


Ufi technology fuel system protection

UFI Technology

Examples of System

Level Testing

Pump Startup Current

APU Load Transient

GPU – APU Switchover


Ufi technology fuel system protection

UFI Technology

Repetitive Auto Shutoff Testing

Auto Shutoff @ Inlet Uncovered

Note: Independent detection. Shutoff sequence not tied to fuel pump pressure determination or other less-reliable aircraft systems.


Ufi technology fuel system protection

UFI Technology

Ground Fault Protection Demonstrated

Line to Ground Fault Detected

Note: Power removed at control relay. Electrical surge not continued upstream to circuit breaker.


Ufi technology fuel system protection

UFI Technology

Arc Fault Protection Demonstrated

Line to Line Fault Detected

Fault mitigated locally regardless of whether origination occurred upstream or downstream of control relay.


Ufi technology fuel system protection

  • FAA Comments Regarding Project No. ST10777LA-T

  • “Based on the review of the UFI 3000 design and system safety assessment the FAA credits the following attributes to the UFI 3000 functionality, effecting the airplane electrical fuel pump system:

  • Transient Fault Detection

  • 1) Line-to-ground current (parallel fault)

  • 2) Line-to-line current (parallel fault)

  • 3) Opened phase (series fault)

  • Steady-State Fault Detection

  • 1) Unbalanced phase currents

  • 2) Out-of-range phase currents

  • C) In response to any of the above electrical faults the UFI 3000 will de-energize the airplane electromechanical relay to shutoff the fuel pump.

  • D) Fuel Pump Auto-Shutoff. The UFI 3000 will de-energize the airplane electromechanical relay to shutoff the pump in response to pump inlet being uncovered, uninterrupted for fifteen (15) seconds”.

  • “Upon review of the applicants position and supporting documentation, the FAA finds that the applicant meets all the applicable requirements including compliance with 14 CFR 25.981 amendment 25-102, for the installation of UFI 3000 in Boeing 737-300 airplanes center wing tank pumps.” (Issue Paper)


Ufi technology fuel system protection

SFAR88 & 14 CFR Part 25 §25.981

Amendment 25-102

• What is SFAR88?

– It is a recently adopted Rule that requires design approval holders of

certain turbine-powered transport category airplanes, and of

any subsequent modifications to these airplanes, to

substantiate that the design of the fuel tank system precludes

the existence of ignition sources within the airplane fuel tanks

– It also requires developing and implementing maintenance and

inspection instructions to assure the safety of the fuel tank

system

– For new type designs it requires compliance to 14 CFR Part 25

§ 25.981 Amendment 102

The FAA has indicated that terminating actions will be mandated to existing AD’s.

Georgios Roussos, FAA Aerospace Engineer, ANM-130S

Presentation: 2003 Seattle ACO DER Seminar

November 4, 2003


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