Test Rig for OBIGGS, accurate to ±0.02% O₂.

Introduction

The Test Rig for OBIGGS is a turnkey ground-station platform built to execute exhaustive qualification, acceptance testing and R&D for On-Board Inert Gas Generating Systems (OBIGGS) destined for military and transport aircraft. By precisely reproducing bleed-air conditions (pressure, temperature, humidity and dynamic transients), this rig validates every critical performance metric — membrane integrity, inert-gas purity, response times and leak tightness — ensuring systems meet or exceed industry and regulatory mandates.

Core deliverables

• Fully sequenced, PLC-driven test profiles with customizable parameters
• High-speed data capture (1 Hz–10 Hz) of pressure, flow, temperature and gas composition
• Auto-generated certification-ready reports and raw data export (CSV/PDF/XML)
• Turnkey installation, operator training and maintenance support

OBIGGS: purpose & application

Why fuel-tank inerting?

Fuel-tank ullage — filled with a fuel–air mixture — becomes explosive if the oxygen fraction exceeds about 12% by volume. Ignition sources include lightning strikes, static discharge, combat damage and high-energy sparking. Inerting displaces oxygen, breaking the combustion triangle (fuel + oxidizer + ignition), thus preventing catastrophic tank explosions.

OBIGGS operation

• 1. Bleed-air extraction: air tapped from the engine compressor section (200–300°C, 4–7 bar).
• 2. Air pre-treatment: multi-stage filtration and heat-exchangers remove particulates, oil carryover and moisture to ISO 8573-1 Class 1.1.1.
• 3. Membrane separation: hollow-fiber membrane bundles selectively permeate O2 and H2O; retained nitrogen-enriched air (NEA) achieves ≥90% N2 purity.
• 4. Ullage inerting: NEA is delivered continuously to the fuel-tank ullage, maintaining O2 ≤10–12%.
• 5. Permeate management: O2-rich exhaust vents overboard or recycles to low-pressure return.

Benefits & use cases

• Survivability: prevents explosion under battle damage or lightning.
• Regulatory compliance: meets FAA/EASA fuel-tank safety rules; MIL-STD-810G and SAE inerting standards.
• Weight & volume savings: no heavy gas bottles — membrane modules are compact and light.
• Continuous protection: inerting maintained throughout all flight phases.
• Low lifecycle cost: minimal moving parts; membrane life >5,000 hr with simple filter changes.

Deployments: F-16, Rafale, Eurofighter, A-330 MRTT, KC-135, military helicopters, UAVs.

System architecture

1. Air supply & regulation

• 8 bar(g) @ 1,000 LPM NTP primary inlet, ISO 8573-1 filtration
• PR-1 (0.5–12 bar, 3,500 LPM) and PR-2 (0.5–7 bar, 1,600 LPM) precision regulators
• Four bi-stable ball valves (–0.95 → +30 bar, 15 mm port) for isolation

2. Flow control & measurement

• Manual needle valves for sweep-rate profiling (1–10 bar)
• Mass flow meters: FM-1 0–100 LPM (±2% F.S.); FM-2 50–500 LPM (±2% F.S.); FM-3/4 94–944 ccm (±2% F.S.) for low-flow

3. Oxygen analysis

• Servomex MiniMP 5200 paramagnetic analyzer
• 0–100% O2 range, ±0.02% accuracy, T90 <15 s
• Automated zero/span calibration; on-board pressure/temperature compensation

4. Control & data acquisition

• Siemens S7-1200 PLC with analog/digital I/O
• 10.1″ HMI touchscreen for real-time control and trending
• Custom SCADA software: test scripting, live charts, CSV/PDF/XML export

Mechanical & environmental design

• Chassis & enclosure: corrosion-resistant 304 SS, powder-coated, tamper-proof panels with quick-release latches.
• Mobility: heavy-duty swivel castors with integrated brakes.
• Thermal management: forced-air ventilation for electronics; optional temperature chamber for environmental stress testing (–20°C to +60°C).
• Service access: color-coded pneumatics, clearly labeled ports, removable panels for rapid maintenance and calibration.

Operational workflow

• 1. Setup & calibration: connect single-point pneumatic and 230 VAC power; run automated analyzer zero/span and system leak-down check (hold at 10 bar for 5 min).
• 2. Test sequencing: define profiles — pressure ramps (0.5 bar steps), flow sweeps (50→500 LPM), temperature cycles; initiate via HMI or SCADA, PLC executes valve actuation and data capture.
• 3. Real-time monitoring: live trending of P_in, ΔP across membrane, flow, O2%; alarm thresholds for over-pressure, O2 deviation, leaks.
• 4. Reporting & analysis: auto-generate certification reports — plots, tables, pass/fail summaries; export raw data for custom analysis (MATLAB, Python, etc.).

Safety, compliance & quality

• Safety interlocks: emergency-stop cuts all power and pneumatic lines; over-pressure relief valves at 16 bar; leak alarm with auto-shutdown.
• Regulatory compliance: CE marking (EMC/LVD), MIL-STD-810G shock/vibration/temperature, ISO 9001:2015 quality assurance.
• Documentation package: First-Article Inspection (FAI) with traceable calibration certificates; IQ/OQ/PQ protocols; FAT/SAT execution templates; full user and maintenance manuals.

Installation, training & after-sales

• Installation: single-point hookups; onsite commissioning by factory engineers; FAT demonstration.
• Training: two days of hands-on operator and maintenance training covering system operation, calibration, troubleshooting and safety procedures.
• Warranty: standard 12 months (extendable to 36 months).
• Maintenance contracts: annual calibration, software updates and priority spare-parts provisioning.
• Remote assistance: secure VPN access for diagnostics and software support.

Conclusion

The Test Rig for OBIGGS equips aerospace OEMs, MRO depots and R&D centers with an uncompromising, end-to-end solution for validating and certifying inert-gas generating systems. Its robust design, exhaustive automation and turnkey support minimize commissioning time and operational risk — delivering peace of mind and compliance in the most demanding flight-safety applications.