ETOPS - Extended Twinned Engine Operations
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ETOPS (Extended Range Twin Engine Operations) is a regulatory framework ensuring twin-engine aircraft can safely operate long distances with specific criteria for one-engine operation. The certification process involves phases of approval based on aircraft reliability, diversionary airfield accessibility, and operational standards, progressively extending maximum flight durations. Effective management and compliance with stringent maintenance and operational standards are crucial for airlines to maintain ETOPS certification and ensure safety.
ETOPS - Extended Twinned Engine Operations
- 1. ETOPS
- 2. ETOPS Extended Range Twin Engined Operations Kelvin Lam, Jul 2016
- 3. Background Older aircraft... Spot the similarity...?
- 4. Background • Tri-/quad jet engines • ↑ fuel consumption = ↑ cost of operation • ↑ maintenance cost • ↓ probability of all engines shutdown
- 5. Background Newer aircraft... Spot the similarity...? Probably not much; they are twinjets.
- 6. Background • ↑probability of all engine shutdown • Can be fatal! • Nowadays, engine reliability ↑ • ↑Aircraft reliability • ↑Longer range capabilities • Therefore, mitigation plan possible: ETOPS certification
- 7. Introduction • ETOPS criteria defines maximum flight duration with one-engine operating, at one engine inoperative speed. • From any plausible critical points, the A/C must be able to land at a diversionary airfield within the ETOPS permitted threshold. • Threshold determined by: A/C & engine manufacturer, aviation authorities, IATA etc.
- 10. 120-minute rule ETOPS black hole Beginning stage of ETOPS
- 11. 138-minute rule After 6 months on 120 mins operations, an additional 15% maybe granted
- 12. 180-minute rule After 12 months on 138 mins operations, with good A/C & engine reliability, 180- mins approval may be granted. This enables almost any commercial routes to be flown. To South America
- 13. What has changed? • Diversionary distance with 1 engine operative (drag) • Descend & cruise speed control (maintaining FL and gentle slope that gives best TAS) • Critical fuel planning, taking engine failure/depressurisation into account
- 14. What has changed? Dispatch-wise... • MNPS & RNP certification and consideration (“perpendicular” to RSVM) • Stringent MMEL extra weight • Additional failsafe navigation systems • Weather minima requirement when route dispatch
- 15. ETOPS critical fuel reserves • In case of engine failure / depressurisation, diversionary scenarios can be like this... Very low efficiency for turbine engines!
- 16. ETOPS critical fuel reserves
- 17. ETOPS critical fuel reserves Gas Turbine Engine – Propulsive Efficiency
- 18. ETOPS critical fuel reserves Higher fuel burn to compensate reduced thrust Gas Turbine Engine – Propulsive Efficiency
- 19. ETOPS critical fuel reserves *NB: not the same as Cost Index / Performance Factor, as this is a safety-critical situation
- 20. Procedure • Complete failure checklist • Inform ATC • Initiate descent • Determine alternate airfield • Divert using pre-planned diversion strategy and speed profile, subject to actual situational evaluation • OFF Fuel X-Feed to faulty engine
- 21. Procedure • OFF Air-Conditioning PACK (reduce engine load) • APU START (maintain blue hydraulic level)
- 22. Diversion distance • Influential factors: A/C Gross Weight at take off ISA atmospheric / metrological condition Diversionary FL = 170 (usual) Never exceed speed: one-engine VMO/MMO Engine choice
- 23. Approval principle • According to EASA AMC 20-6, three criteria is defined to apply for ETOPS approval Type design approval In-service Experience Approval/Continuing Airworthiness Operations Approval
- 24. Type-design approval • Ensures that the aircraft type certification provide... Adequate system redundancy Data supplied for safety assessments Reliability of engine in IFSD situation (In Flight Shut Down)
- 25. In-Service Experience approval • Requires data from world A/C fleet & engine to achieve necessary level of engine reliability collectively • Requires evidence of operator’s capability to maintain & operate ETOPS aircraft • Question to be considered:
- 26. In-Service Experience approval • Requires data from world A/C fleet & engine to achieve necessary level of engine reliability collectively • Requires evidence of operator’s capability to maintain & operate ETOPS aircraft • Question to be considered: “How does the extra cost in ETOPS crew training & hardware certification, justify fuel saving cost in longer timespan?”
- 27. Operations approval • Requires more stringent quality on engine & APU (crucial for maintaining ETOPS airworthiness) • Restrictive MEL aircraft requirement • ETOPS route may have reduced pool of ETOPS-certified A/C due to maintenance input • Reputable & sound forward planning to achieve no ADD (acceptable deferred defect) target for ETOPS
- 28. Operations approval • Significant system: – Adversely affect safety of ETOPS flight when failed; – Its functioning is imperative to a safe diversionary flight
- 29. Operations approval • Significant system: – Adversely affect safety of ETOPS flight when failed; – Its functioning is imperative to a safe diversionary flight FAIL! FAIL! FAIL!FAIL! FAIL! FAIL!FAIL!
- 30. Mitigation Type-design approval In-Service Experience approval Operations approval Monitored by EASA Data supplied Airline maintenance / flight-ops management input HOW?
- 31. ETOPS Management Type-design approval In-Service Experience approval Operations approval Monitored by EASA Data supplied Airline maintenance / flight-ops management input ETOPS MANAGEMENT Evidence sent to EASA from time-to-time...
- 32. ETOPS Management - airline Closer fleet monitoring on repetitive defects ASRs Regular ETOPS meeting/engineering newsletter Airline maintenance / flight-ops management input ETOPS MANAGEMENT Mitigate many inter-related ADDs (iceberg theory) Above & beyond MEL standard
- 33. ETOPS Management - EASA Monitored by EASA Data supplied ETOPS MANAGEMENT Monitors IFSD rates, abnormal power thrust, turnbacks/diversions. Any other significant ETOPS events
- 34. ETOPS Management • When a problem is spotted, airline can consider: Performing less restrictive ETOPS route Honour (most) ADD requests Priority maintenance tasks Call for meetings with stakeholders
- 35. ETOPS Management • To remain ETOPS compliant, airline shall demonstrate – High standard of (paper-work from) maintenance – Low number of ADD – Low number of faults – Good monitoring & management systems
- 36. Conclusion • ETOPS definition & meaning: flight duration, critical point, diversionary • Progressive approval: 60, 120, 138, 180, beyond 180 • ETOPS certifying consideration: dispatch route, critical fuel • ETOPS approval: type-design, in-flight service, operations • ETOPS management: ADD/fleet monitoring, ETOPS meeting