Aircraft fuel tanks are a major component of aircraft fuel systems. They can be classified into internal or external fuel tanks and can be further classified by method of construction or intended use. Safety aspects of aircraft fuel tanks were examined during the investigation of the 1996 TWA Flight 800 in-flight explosion accident.
Integral tanks are areas inside the aircraft structure that have been sealed to allow fuel storage. An example of this type is the "wet wing", commonly used in larger aircraft. Since these tanks are part of the aircraft structure, they cannot be removed for service or inspection. Inspection panels must be provided to allow internal inspection, repair, and overall servicing of the tank. Most large transport aircraft use this system to store fuel in the wings, fuselage and empennage of the aircraft. [1]
Rigid removable tanks are installed in a compartment designed to accommodate the tank. They are typically made of metal, plastic or fibreglass construction, and may be removed for inspection, replacement, or repair. [2] Rigid removable tanks are not relied on for the aircraft's structural integrity. These tanks are commonly found in smaller general aviation aircraft, such as the Cessna 172. Combat aircraft and helicopters generally use self-sealing fuel tanks. [1]
Bladder tanks, bag tanks or fuel cells, are reinforced rubberised bags installed in a section of aircraft structure designed to accommodate fuel. The bladder is rolled up and installed into the compartment through the fuel filler neck or access panel, and is secured by means of snap fasteners or cord and loops inside the compartment. Many high-performance light aircraft, helicopters and some smaller turboprop aircraft use bladder tanks. [1]
Many aircraft designs feature fixed tip tanks mounted at the end of each wing. The weight of the tanks and fuel counteract wing bending loads during manoeuvres and reduce fatigue on the spar structure.[ citation needed ]
Conformal fuel tanks (CFTs) or "fast packs" are additional fuel tanks fitted closely to the profile of an aircraft which extend either the range or endurance of the aircraft, with a reduced aerodynamic penalty compared to external drop tanks. [3]
Drop tanks, external tanks, wing tanks, pylon tanks or belly tanks are all terms used to describe auxiliary externally mounted fuel tanks. Drop tanks are generally expendable and often jettisonable. External tanks are commonplace on modern military aircraft and occasionally found in civilian ones, although the latter are less likely to be discarded except in the event of emergency. [1]
Drop tanks were originally designed to be jettisoned when empty or in the event of combat or emergency in order to reduce drag and weight, increasing manoeuvrability and range. Modern external tanks may be retained in combat, to be dropped in an emergency and are often not designed for the stresses of supersonic flight. [1]
Fuel tanks have been implicated in aviation disasters, being the cause of the accident or worsening it (fuel tank explosion).
The official explanation for the explosion and subsequent crash of TWA Flight 800 is that an explosive fuel/air mixture was created in one of the aircraft's fuel tanks. Faulty wiring then provided an ignition source within the tank, destroying the airliner. [4] While the accuracy of the official findings is still questioned in this case, similar explosions have occurred in other aircraft. It is possible to reduce the chance of fuel tank explosions by a fuel tank inerting system or fire fighting foam in the tanks. [5]
The Boeing 737, for example, has two systems that reduce the chance of a fuel tank ignition. One shuts off fuel pumps when fuel output pressure is low, to prevent them from heating (since they rely on the fuel itself for cooling). The other enriches the nitrogen levels in the air in the fuel tank, so there is insufficient oxygen there for burning. [6] The aircraft engines are also capable of getting fuel via suction in the result of a failure in the backup pumps, though this produces less reliable thrust. [6]
On passenger planes, fuel tanks are often integrated into the wings, and when there are also tanks inside the body of the aircraft, the wing tanks are used preferentially. [7] [6] The placement reduces the stress on the wings during takeoff and flight, by putting the heavy fuel directly inside the source of lift. [7] Putting tanks in the main wings rather than near the tail or nose also reduces the amount of weight that is off-center from the plane's center of gravity, and which changes as it flies [7] and which would make the aircraft less efficient by requiring increased use of elevators. [6] Given their irregular shape and lack of windows, wings are often unusable for storage of cargo or seating of passengers. But their hollow structure makes in-wing fuel storage feasible and an efficient use of space; the presence of structural spars in "wet wing" tanks reduces sloshing. [6] Placement of fuel tanks in the wings also moves them further from passengers and crew in the event of a leak or explosion.[ citation needed ]
Trans World Airlines Flight 800 (TW800/TWA800) was a scheduled international passenger flight from John F. Kennedy International Airport (JFK) in New York City to Fiumicino Airport (FCO) in Rome with a stopover at Charles de Gaulle Airport (CDG) in Paris. On July 17, 1996, at approximately 8:31 p.m. EDT, twelve minutes after takeoff, the Boeing 747-100 serving the flight exploded and crashed into the Atlantic Ocean near East Moriches, New York.
An inerting system decreases the probability of combustion of flammable materials stored in a confined space. The most common such system is a fuel tank containing a combustible liquid, such as gasoline, diesel fuel, aviation fuel, jet fuel, or rocket propellant. After being fully filled, and during use, there is a space above the fuel, called the ullage, that contains evaporated fuel mixed with air, which contains the oxygen necessary for combustion. Under the right conditions this mixture can ignite. An inerting system replaces the air with a gas that cannot support combustion, such as nitrogen.
The Apollo command and service module (CSM) was one of two principal components of the United States Apollo spacecraft, used for the Apollo program, which landed astronauts on the Moon between 1969 and 1972. The CSM functioned as a mother ship, which carried a crew of three astronauts and the second Apollo spacecraft, the Apollo Lunar Module, to lunar orbit, and brought the astronauts back to Earth. It consisted of two parts: the conical command module, a cabin that housed the crew and carried equipment needed for atmospheric reentry and splashdown; and the cylindrical service module which provided propulsion, electrical power and storage for various consumables required during a mission. An umbilical connection transferred power and consumables between the two modules. Just before reentry of the command module on the return home, the umbilical connection was severed and the service module was cast off and allowed to burn up in the atmosphere.
In aviation, a drop tank is used to describe auxiliary fuel tanks externally carried by aircraft. A drop tank is expendable and often capable of being jettisoned. External tanks are commonplace on modern military aircraft and occasionally found in civilian ones, although the latter are less likely to be discarded except in an emergency.
A fuel tank is a safe container for flammable fluids, often gasoline or diesel fuel. Though any storage tank for fuel may be so called, the term is typically applied to part of an engine system in which the fuel is stored and propelled or released into an engine. Fuel tanks range in size and complexity from the small plastic tank of a butane lighter to the multi-chambered cryogenic Space Shuttle external tank.
Pan Am Flight 214 was a scheduled flight of Pan American World Airways from San Juan, Puerto Rico, to Baltimore, and then to Philadelphia in the United States. On December 8, 1963, while flying from Baltimore to Philadelphia, the Boeing 707-121 crashed near Elkton, Maryland. All 81 passengers and crew on the plane were killed. The crash was Pan Am's first fatal accident with the 707, which it had introduced to its fleet five years earlier.
The Boeing Model 307 Stratoliner is an American stressed-skin four-engine low-wing tailwheel monoplane airliner derived from the B-17 Flying Fortress bomber, which entered commercial service in July 1940. It was the first airliner in revenue service with a pressurized cabin, which with supercharged engines, allowed it to cruise above the weather. As such it represented a major advance over contemporaries, with a cruising speed of 220 mph (350 km/h) at 20,000 ft (6,100 m) compared to the Douglas DC-3's 160 mph (260 km/h), at 8,000 ft (2,400 m) then in service. When it entered commercial service it had a crew of five to six, including two pilots, a flight engineer, two flight attendants and an optional navigator, and had a capacity for 33 passengers, which later modifications increased, first to 38, and eventually to 60.
A hardpoint is an attachment location on a structural frame designed to transfer force and carry an external or internal load. The term is usually used to refer to the mounting points on the airframe of military aircraft that carry weapons, ordnances and support equipments, and also include hardpoints on the wings or fuselage of a military transport aircraft, commercial airliner or private jet where external turbofan jet engines are often mounted.
Fuel dumping is a procedure used by aircraft in certain emergency situations before a return to the airport shortly after takeoff, or before landing short of the intended destination to reduce the aircraft's weight.
In a fixed-wing aircraft, the spar is often the main structural member of the wing, running spanwise at right angles to the fuselage. The spar carries flight loads and the weight of the wings while on the ground. Other structural and forming members such as ribs may be attached to the spar or spars, with stressed skin construction also sharing the loads where it is used. There may be more than one spar in a wing or none at all. Where a single spar carries most of the force, it is known as the main spar.
The bomb bay or weapons bay on some military aircraft is a compartment to carry bombs, usually in the aircraft's fuselage, with "bomb bay doors" which open at the bottom. The bomb bay doors are opened and the bombs are dropped when over the target or at a specified launching point.
A wet wing is an aerospace engineering technique where an aircraft's wing structure is sealed and used as a fuel tank.
TWA Flight 800 conspiracy theories are discredited alternative explanations of the crash of Trans World Airlines Flight 800 in 1996. The NTSB found that the probable cause of the crash of TWA Flight 800 was an explosion of flammable fuel/air vapors in a fuel tank, most likely from a short circuit. Conspiracy theories claim that the crash was due to a U.S. Navy missile test gone awry, a terrorist missile strike, or an on-board bomb. In 2013, a documentary alleging that the investigation into the crash was a cover-up made news headlines with statements from six members of the original investigation team, now retired, who also filed a petition to reopen the probe.
Philippine Airlines Flight 143 (PR143) was a domestic flight from Manila Ninoy Aquino Airport, Manila, to Mandurriao Airport, Iloilo City, Philippines. On May 11, 1990, at Manila Ninoy Aquino International Airport the Boeing 737-300 assigned to the route suffered an explosion in the central fuel tank and was consumed by fire in as little as four minutes. This accident marked the first hull loss of a 737-300.
ATA 100 contains the reference to the ATA numbering system which is a common referencing standard for commercial aircraft documentation. This commonality permits greater ease of learning and understanding for pilots, aircraft maintenance technicians, and engineers alike. The standard numbering system was published by the Air Transport Association on June 1, 1956. While the ATA 100 numbering system has been superseded, it continued to be widely used until it went out of date in 2015, especially in documentation for general aviation aircraft, on aircraft Fault Messages and the electronic and printed manuals.
An aircraft fuel system allows the crew to pump, manage, and deliver aviation fuel to the propulsion system and auxiliary power unit (APU) of an aircraft. Fuel systems differ greatly due to different performance of the aircraft in which they are installed. A single-engine piston aircraft has a simple fuel system; a tanker, in addition to managing its own fuel, can also provide fuel to other aircraft.
Thai Airways International Flight 114, a Thai Airways International Boeing 737-400 bound for Chiang Mai from Don Mueang International Airport in Bangkok, was destroyed by an explosion of the center fuel tank resulting from ignition of the flammable fuel/air mixture in the tank while the aircraft was parked prior to boarding on the ground on 3 March 2001. The source of the ignition energy for the explosion could not be determined with certainty, but the most likely source was an explosion originating at the center wing tank pump as a result of running the pump in the presence of metal shavings and a fuel/air mixture. One flight attendant died.
Palair Macedonian Airlines Flight 301 was a scheduled international passenger flight from Skopje to Zurich, operated by Palair Macedonian, the then-flag carrier of Macedonia, now called North Macedonia. On 5 March 1993, the aircraft operating the flight, a Fokker 100, crashed shortly after taking off from Skopje Airport in snowy conditions. Out of the 97 passengers and crew members on board, only 14 survived. At the time, it was the deadliest air disaster in North Macedonia.
In aviation, to jettison is to discard fuel, external stores or other expendable items. The item is usually jettisoned by operating a switch or handle; external stores may be separated from the aircraft by use of explosive bolts or a mechanism.
Imperial Iranian Air Force Flight 48 was a military cargo flight from Tehran, Iran, to McGuire Air Force Base in the United States with a stopover in Madrid, Spain. On May 9, 1976, the Boeing 747-131 freighter operating the flight crashed during its approach to Madrid, killing all 17 people on board.
