Advanced Aviation Training Ltd

ETOPS/LROPS ETOPS (Extended-range Twin-engine Operational Performance Standards) is an acronym for an International Civil Aviation Organization (ICAO) rule permitting twin-engined commercial air transports to fly routes that, at some points, are farther than a distance of 60 minutes flying time from an emergency or diversion airport with one engine inoperative. ETOPS is read (humorously) by employees of the airline industry as Engines Turn or Passengers Swim. This definition allows twin-engined airliners—such as the Airbus A300, A310, A320, A330 and A350 families, and the Boeing 737, 757, 767, 777 and 787 —to fly long distance routes that were previously off-limits to twin-engined aircraft. Contrary to popular/mistaken belief, ETOPS operation has no direct correlation to water, nor distance over water. It refers strictly to single-engine flight times between suitable diversion airfields; regardless as to whether such fields are separated by water, deserts, polar expanses, recurrent (i.e. night-time) airport closures, etc. ETOPS may be replaced by a newer system, referred to as LROPS (Long Range Operational Performance Standards), which will affect all civil airliners, and not merely those with a twin-engine configuration. Government-owned aircraft (including military) do not have to adhere to ETOPS. Until the mid-1980's, the term EROPS (extended range operations) was used before being superseded by ETOPS usage.

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History The first direct transatlantic crossing was made in 1919, in 16 hours, by pilots Alcock and Brown with a twin engined Vickers Vimy. Due to the unreliability of internal combustion engine|piston engines at the time, long distance flight using twin engines was considered risky. A flagship of the piston era, the 4-engined Lockheed Constellation airliner, was regarded as so unreliable that it was jokingly dubbed "the most reliable 3engined airplane flying! Generally with piston engines, having four of them for flying long distances over inhospitable terrain or sea was a must - arrivals at destination airports on "three turning, and one stopped and with prop feathered", was a common occurrence with any four-engine piston type, not just Constellation. The FAA in 1953, having recognised piston engine limitations, introduced the "60-minute rule" for 2 engine aircraft. This rule states that the flight path of these types of aircraft shall not be further than 60 minutes flying time from an adequate airport. This forced these aircraft, on certain routes, to fly a dogleg path to stay within regulations; they were totally excluded from certain routes due to lack of en-route airports. The 60-minute period is also called 60-minute diversion period. The totally excluded area is called the Exclusion Zone.

Early turbine engine experience Turbine engines such as the Pratt & Whitney JT8D series in the 1950s and 1960s demonstrated that they had much higher thrust and reliability than any then available piston engines. It was then powering the 2-engined Boeing 737 series and 3-engined Boeing 727. Because of its excellent record, the "60-minute rule" was waived for 3-engined. This opened the way for the development of widebody intercontinental trijets such as the Tristar and DC-10. By then only 2-engined jets were restricted by the "60-minute rule".

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Early twin-engine high-bypass turbofan airliners Outside the USA, other countries followed ICAO regulations, which allowed for 90 minutes' diversion time. This fact was exploited by Airbus, launching the world's first twin-engined high-bypass turbofan engine Wide-body airliner, the Airbus A300, in 1974. It was about three quarters the size of DC-10s and Tristars and for an equivalent load for the same distance and cheaper to operate. As a result, twin-engined aircraft like the A300, Boeing 737 and 767 became very popular alternatives to three and four-engined aircraft.

Early ETOPS experience All the developments in aircraft technologies have led the FAA and the ICAO to realise that it is safe for a properly designed twin-engined airliner to conduct intercontinental transoceanic flights. The guidelines issued form the ETOPS regulations. The FAA was the first to approve ETOPS guidelines in 1985. It spelled out conditions that need to be fulfilled for a grant of 120 minutes' diversion period, which is sufficient for direct transatlantic flights. Today, ETOPS forms the bulk of transatlantic flights.

Boeing 767-300ER, the ETOPS pioneer The U.S. Federal Aviation Administration gave the first ETOPS rating in May of 1985 to Trans World Airlines for Boeing 767 service between St. Louis and Frankfurt, allowing TWA to fly its aircraft up to 90 minutes away from the nearest airfield: this was later extended to 120 minutes after a federal evaluation of the airline's operating procedures.

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ETOPS extensions In 1988, the FAA amended the ETOPS regulation to allow the extension to 180 minutes diversion period subject to stringent technical and operational qualifications. This made 95% of the earth's surface available to ETOPS flights. The first such flight was conducted in 1989. This set of regulations was subsequently adopted by the JAA, ICAO and other regulatory bodies worldwide. In this manner the B737, 757 and 767 series, the Airbus A300-600, 310, 320 and 330 series were approved for ETOPS operations. The success of ETOPS aircraft like 767 and 777 killed the intercontinental trijets. This ultimately led Boeing to end the MD-11 program a few years after Boeing's merger with McDonnell Douglas, as well as to scale down the production of its own Boeing 747. The North Atlantic airways are the most heavily utilized oceanic routes in the world. Most are conveniently covered by ETOPS-120min rules, removing the necessity of utilizing 180-min rules. However, many of the North Atlantic diversion airports, especially those in Iceland and Greenland, are frequently subject to adverse weather conditions making them unavailable for use. As the 180-min rules is the upper limit, the JAA has given 15% extension to the 120-min rules to deal with such contingencies, giving the ETOPS-138min thereby allowing ETOPS flights with such airports closed.

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Early ETOPS

Boeing 777-200ER. The regulations allow an airliner to have ETOPS-120 rating on its entry into service. ETOPS-180 is only possible after 1 year of trouble-free 120-min ETOPS experience. Boeing has convinced the FAA that it could deliver an airliner with ETOPS-180 on its entry into service. This process is called Early ETOPS. Thus the B777 was the first aircraft to carry an ETOPS rating of 180-min at its introduction. The JAA, however disagreed and the Boeing 777 was rated ETOPS-120 in Europe on its entry into service. European airlines operating the 777 must demonstrate 1 year of trouble-free 120-min ETOPS experience before obtaining 180-min ETOPS for the 777.

ETOPS exclusions Private jets are exempted from ETOPS by the FAA, but are subject to the ETOPS-120 minute rule in the JAA's jurisdiction. Several commercial airline routes are still off-limits to twinjets because of ETOPS regulations. They are routes traversing the South Pacific (e.g. Auckland Santiago), Southern Indian Ocean (e.g. Perth - Johannesburg) and Antarctica (e.g. Auckland - Buenos Aires).

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Beyond ETOPS-180 Effective February 15, 2007, the FAA ruled that US-registered twin-engined airplane operators can fly over most of the world other than the South Polar Region, a small section in the South Pacific, and the North Polar area under certain winter weather conditions provided that the inflight shutdown rate is 1 in 100,000 engine hours. This limit is more stringent than ETOPS-180 (2 in 100,000 engine hours). The qualified aircraft must have appropriate fire-suppression systems, adequate oxygen supplies for crew and passengers (to continue high altitude flight) in the event of depressurisation, and automated defibrillators. Weather reporting, training, and diversion accommodation requirements remain unchanged. Since aircraft occasionally divert for non-engine mechanical problems or passenger medical emergencies, the rule requires that airplane systems be able to support lengthy diversions in remote and sometimes harsh environments. The rules do not apply to 3 or 4 engined cargo aircraft and freed twinjets from ETOPS constraints. EASA distinguishes between twin-engine (ETOPS) and aircraft with 3 or 4 engines. Rules governing such aircraft (3 or 4 engines) are covered under LROPS rules. LROPS would demand similar rules with regard to emergency oxygen and fire-suppression. EASA is expected to release rules for ETOPS and LROPS in 2008.

ETOPS ratings The following ratings are awarded under current regulations according the capability of the airline: • • • •

ETOPS-75 ETOPS-90 ETOPS-120/138 ETOPS-180/207

However, ratings for ETOPS type approval are fewer. They are: • • •

ETOPS-90, which keeps pre-ETOPS Airbus A300B4 legally operating under current rules ETOPS-120/138 ETOPS-180/207, which covers 95% of the earth's surface.

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Approval for ETOPS ETOPS approval is a two-step process. Firstly, the aircraft airframe and engine combination must satisfy the basic ETOPS requirements during its type certification. This is called ETOPS type approval. Such tests may include shutting down an engine and flying the remaining engine during the complete diversion time. Often such tests are performed in the middle of the oceans. It must be demonstrated that, during the diversion flight, the flight crew is not unduly burdened by extra workload due to the lost engine and that the probability of the remaining engine failing is extremely remote. For example, if an aircraft is rated for ETOPS-180, it means that it should be able to fly with full load and just one engine for 3 hours. In addition to operating aircraft which are appropriately type-rated, an operator who conducts ETOPS flights must satisfy his own country's aviation regulators about his ability to conduct ETOPS flights. This is called ETOPS operational certification and involves compliance with additional special engineering and flight crew procedures on top of the normal engineering and flight procedures. Pilots and engineering staff must be specially qualified and trained for ETOPS. An airline with extensive experience operating long distance flights may be awarded ETOPS operational approval immediately, others may need to demonstrate ability through a series of ETOPS proving flights. An ETOPS operational approval rating cannot exceed the ETOPS type approval rating of a fixed-wing aircraft. Regulators closely watch the ETOPS performance of both type certificate holders and their affiliated airlines. Any technical incidents prejudicial to an ETOPS flight must be recorded. From the data collected globally, the reliability of the particular airframe-engine combination is measured and statistics published. The figures must be within limits of type certifications. Of course, the figures required for ETOPS-180 will always be more stringent than ETOPS-120. Unsatisfactory figures would lead to a downgrade, or worse, suspension of ETOPS capabilities either for the type certificate holder or the airline.

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Extended-range twin-engine operations (ETOPS) have become common practice in commercial aviation over the last 15 years. Maintenance and operational programs for the twinjets used in these operations have received special emphasis, and reliability improvements have been made in certain airplane systems. Many operators are now considering the merits of the ETOPS maintenance program for use with non-ETOPS airplanes. An increasing number of operators are now providing ETOPS service to their passengers. For example, 76 percent of 767 operators and 42 percent of 757 operators are flying ETOPS routes. Several operators have discovered that the cost of ETOPS maintenance, compared to its benefits, also offers them a significant cost advantage when flying their non-ETOPS routes and when operating their non-ETOPS airplanes. In 1953, the United States developed regulations that prohibited two-engine airplanes from routes more than 60 min (single-engine flying time) from an adequate airport. These regulations were later formalized in U.S. Federal Aviation Administration (FAA) Federal Aviation Regulation 121.161. The ETOPS program, as outlined in FAA Advisory Circular (AC) 120-42A, allows operators to deviate from this rule under certain conditions. By incorporating specific hardware improvements and establishing specific maintenance and operational procedures, operators can fly extended distances up to 180 min from the alternate airport. These hardware improvements were designed into Boeing 737-600/-700/ -800/-900 and 777 airplanes.

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The ETOPS maintenance approach that can be applied to all commercial airplanes includes

1. 2. 3. 4.

Engine health monitoring. Pre-departure service check. Basic and multiple-system maintenance practices. Event-oriented reliability program.

1. ENGINE HEALTH MONITORING ETOPS maintenance procedures were created to ensure the safety and reliability of flights operating at extended distances from alternate airports and to prevent or reduce the probability of a diversion or turnback with one engine out. These maintenance procedures are equally effective for any commercial airplane with any number of engines. Most traditional maintenance programs are based on regularly scheduled preventive maintenance and on the ability to predict or anticipate maintenance problems by studying failure rates, removal rates, and other reliability data. However, the ETOPS philosophy is a real-time approach to maintenance and includes continual monitoring of conditions to identify problems before they threaten airplane operation or safety. Two items in the ETOPS maintenance program that best illustrate this real-time approach are oil consumption monitoring and engine condition monitoring. Oil consumption monitoring. A typical maintenance program requires checking engine oil before every flight (but only once each day on the 737, as approved by the FAA) and the auxiliary power unit (APU) oil less frequently (such as every 100 hr). The quantity of oil added and flight hours for each leg should be noted in the maintenance logbook.

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The oil consumption rate, the amount of oil used per hour of operation on the previous flight leg, should be calculated for both engines and the APU during ETOPS before dispatch. The resulting number provides a better indication of oil usage or loss than the quantity of oil added. If the rate is acceptable, the flight can be released; if not, the cause of the increased usage must be addressed before dispatching the airplane on an ETOPS flight. This increase can frequently be caused by an oil leak, which is easy to detect and repair. The consumption rate data is also logged to track long-term variations in consumption rates (fig. 1). This allows the operator to determine if problems are developing so they can identify and implement solutions before serious engine or APU degradation occurs.

Figure 1. Oil Consumption Rate

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Advanced Aviation Training Ltd Engine condition monitoring (ECM). For many years, ECM computer programs have been available for all engines used on Boeing airplanes. The engine manufacturer supplies ECMs to help operators assess the general health of their engines. The programs allow for monitoring of such parameters as N1, N2, exhaust gas temperature, fuel and oil pressures, and vibration (fig. 2). Most operators use an ECM program regardless of whether they fly ETOPS routes. ETOPS operators are required to use ECMs to monitor adverse trends in engine performance and execute maintenance to avoid serious failures. These failures could cause in-flight shutdowns, diversions, or turnbacks. In some cases, oil consumption data and ECM data can be correlated to define certain problems.

Figure 2. Typical 757/767 EICAS display

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Flight crew records values after reaching stable cruise; readings are relayed to ground personnel.

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2. PREDEPARTURE SERVICE CHECK FAA AC 120-42A requires certain ETOPS systems to be checked before each flight. Boeing determined that the transit check in the maintenance planning data document was sufficient to meet the AC requirement. This is because certain systems relating to ETOPS were redesigned for greater reliability and dispatch requirements were altered for ETOPS (e.g., minimum equipment list requirements). However, because of the oil consumption monitoring requirements for ETOPS, the APU check interval on the 737, 757, and 767 was changed to the transit check for ETOPS airplanes. The engine oil servicing interval changed only on the 737. These two changes and the calculation of consumption rate are the only changes necessary to the standard transit check to form the ETOPS pre-departure service check.

3. BASIC AND MULTIPLE-SYSTEM MAINTENANCE PRACTICES Two programs -- resolution of discrepancies and avoidance of multiple similar system maintenance -- are outlined in AC 120-42A. Resolution of discrepancies. This program requires items that are repaired or replaced to be checked for proper installation and operation before the work is signed off on the maintenance log. This ensures that the item is actually fixed and that no new problems were introduced during maintenance. This maintenance practice is applicable to all airplanes. Avoidance of multiple similar systems maintenance. Maintenance practices for the multiple similar systems requirement were designed to eliminate the possibility of introducing problems into both systems of a dual installation (e.g., engines and fuel systems) that could ultimately result in failure of both systems. The basic philosophy is that two similar systems should not be maintained or repaired during the same maintenance visit. Some operators may find this difficult to implement because all maintenance must be done at their home base. However, methods exist for avoiding the problems that may be introduced by working on two similar systems simultaneously for example, different personnel can perform the required work on the similar systems, or they can ask each other to review the work done on each system. If the systems are checked after performing maintenance according to the resolution of discrepancies program, any problems introduced during maintenance should be identified and corrected before releasing the airplane for flight.

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4. EVENT-ORIENTED RELIABILITY PROGRAM An event-oriented reliability program associated with ETOPS differs from conventional reliability programs, which rely on historical data or alert levels to determine when an item should be investigated for possible corrective action. In an event-oriented reliability program, each event on an ETOPS-significant system is investigated to determine if a problem could be reduced or eliminated by changing the maintenance program. Examples of events include a failure, removal, or pilot report. Events can also be monitored to detect long-term trends or repeat items. Not all events warrant such detailed investigations; continual monitoring and awareness of problem areas reflects the ETOPS real-time maintenance philosophy. SUMMARY Although three- and four-engine Boeing airplanes (as well as some earlier 737s) are not specifically designed or approved for ETOPS, the ETOPS maintenance approach can be applied to those airplanes and offer operators significant improvements in reliability, performance, and dispatch rates. The approach can be applied at minimal cost, which can later be offset by reduced maintenance costs and other costs associated with diversions or turn backs.

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OPERATOR EXPERIENCE WITH ETOPS MAINTENANCE United Airlines (UAL) maintains all its 767 airplane engines and auxiliary power units (APU) in ETOPS configuration, regardless of whether the airplane is used in ETOPS flights. This provides greater maintenance flexibility and reduces the need to carry different engine configurations to supply both ETOPS and non-ETOPS fleets. Since 1990, UAL has experienced a constant decrease in its in-flight shutdown (IFSD) rate (fig. 1).

Figure 1. United Airlines IFSD Rate

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By 1991, UAL achieved a level of reliability that permitted qualifying its 747-100s for ETOPS if necessary. By applying ETOPS maintenance techniques to both engines and other systems on non-ETOPS airplanes, UAL increased the overall reliability of its 747 fleet and 767-200s (fig. 2).

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Advanced Aviation Training Ltd Figure 2. ETOPS Maintenance and Engine Reliability

Trans World Airlines (TWA) recognized the benefits of ETOPS awareness to maintenance early in its experience with the 767. Many aspects of the ETOPS programs were incorporated into its non-ETOPS fleets. Line mechanics working on 747s also received 767 ETOPS training; as a result, TWA saw an improvement in its 747 dispatch rate. The ETOPS philosophy has now spread fleet wide at TWA and is a contributing factor to the operator’s ability to meet on-time performance goals. The TWA 767 and 757 airframes and engines are all maintained in ETOPS configuration. As with UAL, TWA sees an advantage in operational flexibility, purchasing spares for a reduced number of configurations, and standardized training and documentation for the ETOPS approach. The number of other operators who have realized benefits from adopting the ETOPS approach to maintenance continues to grow.

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