# Presentation: 284160

## FAA Concept OBIGG System Flight Testing on NASA 747 SCA

- William CavageAAR-440 Fire Safety ResearchFederal Aviation Administration

## Outline

- Goals and Objectives
- OBIGGs Architecture
- OBIGGs Installation
- Pallet
- NEA Deposit
- Instrumentation / DAS
- CWT
- System
- OBOAS / FAS
- Data Acquisition
- Power Distribution
- Status

## Testing Goals and Objectives

- Prove the simplified inerting concept and validate/expand upon existing system performance models
- Develop/validate system sizing data
- Validate previous in flight inert gas distribution modeling done by FAA
- Measure the progression of flammability in the CWT of a typical commercial transport airplane

## OBIGGS - System Architecture

- 400 deg F bleed air enters electrically controlled & operated Shut-off Valve on OBIGGS Control Box
- Air goes through heat exchanger by a cooling air throttling valve to control temperature manually using a ASM air input temperature sensor
- Some bleed air can bypass the heat exchanger if selected
- Conditioned air passes through dust/oil contaminant filter
- Air enters ASM and has OEA separated and dumped overboard

## OBIGGS - System Architecture (cont’d)

- NEA passes through high flow shut-off valve (Parker Box operator) and High/Low flow metering valves
- System controlled by control box in cabin that is connected to system with cable routed through wheel well
- Turns system on/off
- Select heat exchanger bypass on/off
- Select fan on/off
- Select high/low flow mode
- ASM input air temperature readout

## Assembled FAA OBIGGs Drawing

## OBIGGS - System Installation

- System installed in aft, right side fairing area (empty pack bay)
- System is mostly assembled before installation in the aircraft
- Total Weight = 165 lbs
- System attaches to fairing structure at six locations with specially design mounting brackets
- Brackets designed by Shaw for canceled FAA joint flight test with Boeing
- 4 main brackets pick up existing fastener holes but two secondary brackets need to have holes drilled in stringer
- System wired to control box in cabin via a cable which attaches to the system 41-pin connector
- Powers/controls system components

## OBIGGS - System Installation (cont’d)

- System interfaces with bleed system via a main bleed duct manifold in that area
- 4-foot segment from SCA is removed and FAA segment installed
- Needs to align precisely with system bleed air input fitting
- System cooling air passes in a scoop and out the outflow box
- Two FAA panels with these parts already mated with aircraft

## Top View of System Installed

- Inboard Aircraft
- Structure

- Outboard Aircraft
- Structure

## Simplified OBIGG System Installation

## Empty Pack Bay Before/After System Installation

## OBIGGS - Deposit System

- Install deposit “T” and dual isolation valves allows for improved functionality of testing (counter-wire valves)
- Install a “T” in system NEA deposit
- 1 side of “T” goes to outflow box via a normally closed isolation valve
- Other side of “T” goes to flow meter, check valve, and a second normally open isolation valve
- Install AN bulkhead fitting in replaced pack bay canted bulkhead panel
- Route NEA from check valve to fitting with flexible hose

## Deposit System Overview

## NEA Deposit “T”

## Flow Meter/Deposit Installation

## NEA Diversion Valve Installation

## OBIGGS - Deposit System (cont’d)

- NEA fitting is 1” SwageLok Bulkhead Fitting
- NEA routed to deposit nozzle mounted in the top of tank in Bay 6 (aft, right bay) via a 1-inch flexible line
- nozzle mounted in bracket attached to aircraft stiffener bracket between strings at top of tank
- Also Blocked Half Vent System

## Install Instrumentation Port 

## Existing Stringer/Stiffener/Bracket Assembly

## Install NEA Deposit Nozzle and Associate Hardware

## Install Vent Blocking Plates 

## Instrumentation and Data Acquisition

- Various thermocouples and pressure transducers used
- Evaluate system performance
- Measure tank flammability parameters
- OBIGGS system flow meter and 2-channel oxygen analyzer for NEA and OEA analysis
- Onboard Oxygen Analysis System (OBOAS) most critical measurements
- 8-channel system analyzes 8 locations in tank
- Flammability Analysis System (FAS) will measure progression of CWT flammability in flight
- 1 location in forward section of tank

## CWT Instrumentation

- Installation Instrumentation in the CWT of the NASA SCA
- Install Instrumentation Panel in Place of Purge Door
- Route and Mount Thermocouples
- Install Sample Port Float Valve Assembly and Route Lines as well as sample return lines
- Sub-Contractor (FFC) supported FAA installation
- Highly experienced in this type of work
- Statement of Work gives more details

## Route and Mount Thermocouples 

## Install Sample Port Float Valve Assembly

## Instrumentation - Additional Thermocouples

- Use 16th Inch SS Sheath T-Type Thermocouple Probes
- Install one in each used pack bay and one in the OBIGGS pack bay
- Install 4 in the area of the bleed air connection
- Monitor for Bleed Air Leaks
- System has 6 thermocouples installed
- Thermocouple in cabin
- Thermocouples in measurement systems (OBOAS/FAS)

## Instrumentation - Pressure Transducers

- Potential to add 1 to bleed manifold if possible
- Purchase off-the-shelf lab pressure transducers
- Sensotec TJE Precision, Absolute series
- Run on 28 VDC, 12 VDC nominal bridge voltage, internally regulated
- 0-5 VDC output
- Mount transducers on panel in cabin
- Run 5 sense lines to pack bay

## Thermocouple Probe and Pressure Transducer

## Instrumentation - NEA Flow Meter

- Engineered Specifically for The FAA OBIGGS
- Designed from Existing Commercial and Military Assemblies  by FCI
- Flight worthy instrumentation (No TSO)
- Uses vortex shedding heat release principal
- Also measures absolute temperature and pressure of flow
- 1” diameter flow tube integrates with existing deposit system on pallet

## Flow Meter 

## System Instrumentation Diagram 

- Static Pressure

- Temperature

- Spare [O2]

- Static Pressure

- Temperature

- OEA [O2]

- Temperature

- Static Pressure

- Temperature

- Temperature (FAA Reader)

- Static Pressure

- Temperature

- NEA [O2]

- Penetration
- Hole

## Instrumentation - OBOAS

- Two 4-Channel Systems Measure Oxygen Concentration Continuous at 8 Different Fuel Tank Locations
- Large diaphragm pump draws sample
- Actively controls sample inlet and outlet pressure.
- Flow through sensor design
- Fluid traps, Ejector/Evacuator, Flame Suppressors for Safety
- Mounts in standard 19” flight test half rack including sample system (OBUSS) contained in large, purged box

## OBOAS Block Diagram 

- Fuel Tank Vapor
- Fuel Tank Liquid
- Pressurized Air
- Electrical Power
- Electronic Signals

## OBOAS Mounted in FAA AMCO Racks 

## Instrumentation - FAS

- System uses a Non-Dispersive Infrared Analyzer (NDIR) to measure fuel tank flammability in the form of total hydrocarbons (THC)
- Sample stream must be heated at all points leading to the NDIR to prevent condensation of fuel vapors
- This is achieved in part via three heated hoses
- Installs in a rack and pallet for flight test

## Cabin Instrumentation/Rack Diagram 

- Cabin Instrumentation/Rack Diagram

## Instrumentation - Power Distribution

- 3-Phase 115 VAC 400Hz to Each OBOAS (13 amps/leg)
- 20 Amps of 115 VAC 60 Hz to FAS
- 5 Amps of 115 VAC 60 Hz to DAS and Computer
- OBIGGS takes 5 Amps 28 VDC and 3-Phase 115 VAC, 400Hz (5 Amps/ Leg)
- Each OBOAS converter is tied to a switching unit that allows for power to be distributed between racks and to the OBIGGS O2 analyzer

## Power Distribution Diagram 

## Data Acquisition System

- 16-bit 200 kHz A/D Converter
- Daisy chains slave units with 3-boards each
- Expandable up to 256 channels
- Specified approximately 78 channels of data
- CWT / OBOAS/ FAS - 48 channels
- System Instrumentation - 15 channels
- Misc. Temperatures - 9 channels
- Aircraft Parameters - 2 channels

## Data Acquisition System

**Data**

**Data**

**Daqbook  / 2000E**

**DBK60  Expansion**

## Status

- OBIGGs, OBOAS, FAS, instrumentation/racks, & DAS installation approved
- One sticking point
- OBOAS modified from Airbus testing and FAS completed
- Additional parts purchased
- NEA deposit completed,
- Instrumentation racks built up
- Preparing to ship all equipment for installation