Gust lock

A gust lock on an aircraft is a mechanism that locks control surfaces and keeps open aircraft doors in place while the aircraft is parked on the ground and non-operational. Gust locks prevent wind from causing unexpected movements of the control surfaces and their linked controls inside the aircraft, as well as aircraft doors on some aircraft. Otherwise wind gusts could cause possible damage to the control surfaces and systems, or nearby people, cargo, or machinery. Some gust locks are external devices attached directly to the aircraft's control surfaces, while others are attached to the flight controls inside the cockpit.

GUST LOCK ON RUDDER (1373262822)
Gust lock on a rudder.

Safety

A gust lock can pose a serious safety hazard if its removal is omitted before an aircraft's takeoff, because it renders the flight control inoperative. Many internal gust locks have a safety feature that locks out the aircraft's throttle or engine-start controls until removed and stowed. External-only gust locks typically lack this safety feature, and must be tagged with a large red Remove before flight streamer.

Boeing Model 299 crash
The prototype of the B-17's crash on October 30, 1935

The very first example built of the Boeing B-17 Flying Fortress, the initial Model 299 aircraft, was lost in just this way on October 30, 1935, when its self-contained gust locks were left engaged, with the resulting crash killing Boeing chief test pilot Leslie Tower, and United States Army Air Corps test pilot Ployer Peter Hill. Less than a year later, German Luftwaffe Generalleutnant Walter Wever lost his life in a similar accident from gust lock neglect, when his Heinkel He 70 Blitz monoplane crashed on June 3, 1936, from the Blitz's aileron gust locks not being disengaged before takeoff. Prince Gustaf Adolf of Sweden, the American singer and actress Grace Moore and 20 others were killed in 1947 during the crash of a KLM flight at Copenhagen Airport due to the flight crew forgetting to disengage the gust lock on the tail fin of the aircraft. The crash of Air Indiana Flight 216 occurred due to failure to remove the gust locks.

A C-124 transport carrying US servicemen home for Christmas crashed in 1952 due to engagement of gust locks.

Dan-Air Flight 0034, a Hawker Siddeley 748 series 1 (registration G-BEKF) operating an oil industry support flight crashed on 31 July 1979 at Sumburgh Airport in the Shetland Islands. The aircraft failed to become airborne, ran through the perimeter fence, and crashed into the sea. The accident was due to the elevator gust lock having become re-engaged, preventing the aircraft from rotating into a flying attitude. The aircraft was destroyed and 17 of the 47 people on board drowned.

On May 24, 2014, a gust lock left in place caused the crash of a Gulfstream IV at Hanscom Field, killing Philadelphia Inquirer co-owner Lewis Katz as well as six others.[1]

As these many tragedies (and this is far from a complete list) illustrate, when a gust lock is used, its disengagement is a very important step on the preflight checklist.

References

  1. ^ https://www.usatoday.com/story/news/2015/09/09/ntsb-bedford-crash-gulfstream-philadelphia-inquirer-lewis-katz/71922242/

"Gust lock". The Illustrated Encyclopedia of Aviation and Space. 6. Los Angeles: A.F.E. Press. 1971. p. 1043. LCCN 68014013.

Aircraft dope

Aircraft dope is a plasticised lacquer that is applied to fabric-covered aircraft (both full-size and flying models). It tightens and stiffens fabric stretched over airframes, which renders them airtight and weatherproof.Typical doping agents include nitrocellulose, cellulose acetate and cellulose acetate butyrate. Liquid dopes are highly flammable; nitrocellulose, for instance, is also known as the explosive propellant "guncotton". Dopes often include colouring pigments to facilitate even application, and are available in a wide range of colors.Dope has been applied to various aircraft fabrics, including madapolam, but also more recently on polyester and other fabrics with similar fine weave and absorbent qualities.

Autobrake

An autobrake is a type of automatic wheel-based hydraulic brake system for advanced airplanes. The autobrake is normally enabled during takeoff and landing procedures, when the aircraft's longitudinal deceleration system can be handled by the automated systems of the aircraft itself in order to keep the pilot free to perform other tasks.

Cruciform tail

The cruciform tail is an aircraft empennage configuration which, when viewed from the aircraft's front or rear, looks much like a cross. The usual arrangement is to have the horizontal stabilizer intersect the vertical tail somewhere near the middle, and above the top of the fuselage. The design is often used to locate the horizontal stabilizer away from jet exhaust, propeller and wing wake, as well as to provide undisturbed airflow to the rudder.

Dan-Air Flight 0034

Dan-Air Flight 0034 was a fatal accident involving a Hawker Siddeley HS 748 series 1 turboprop aircraft operated by Dan-Air Services Limited on an oil industry charter flight from Sumburgh Airport, Shetland Islands, to Aberdeen Airport.

The crash, which occurred on 31 July 1979 50 m (160 ft) offshore following the aircraft's failure to take off, resulted in the aircraft's destruction and 17 deaths of 47 on board (15 of 44 passengers and both pilots).

Deceleron

The deceleron, or split aileron, was developed in the late 1940s by Northrop originally for use on the F-89 Scorpion fighter aircraft. It is a two-part aileron that can be deflected as a unit to provide roll control, or split open to act as an air brake. Decelerons are also used on the Fairchild Republic A-10 Thunderbolt II and the Northrop B-2 Spirit flying wing. In differential use they impart yaw moment, potentially obviating the rudder and vertical stabilizer control surface, although requiring active flight control.

Elevator (aeronautics)

Elevators are flight control surfaces, usually at the rear of an aircraft, which control the aircraft's pitch, and therefore the angle of attack and the lift of the wing. The elevators are usually hinged to the tailplane or horizontal stabilizer. They may be the only pitch control surface present, and are sometimes located at the front of the aircraft (early airplanes) or integrated into a rear "all-moving tailplane", also called a slab elevator or stabilator.

Landing gear extender

Landing gear extenders are devices used on conventional or tailwheel-equipped aircraft. They move the wheels forward of the landing gear leg by 2-3 inches (5–8 cm).The installation of landing gear extenders is almost always the result of operational experience with an aircraft design that shows a problem with the landing gear – when the brakes are applied heavily the aircraft has a tendency to go up on its nose and strike the propeller on the ground. The landing gear extenders move the wheels forward relative to the centre of gravity, thus reducing this tendency.Landing gear extenders were optional factory equipment on the late-1940s Cessna 120 and 140.

Leading edge

The leading edge is the part of the wing that first contacts the air; alternatively it is the foremost edge of an airfoil section. The first is an aerodynamic definition, the second a structural one.

As an example of the distinction, during a tailslide, from an aerodynamic point of view, the trailing edge becomes the leading edge and vice versa but from a structural point of view the leading edge remains unchanged.

Longeron

In engineering, a longeron is a load-bearing component of a framework. The term is commonly used in connection with aircraft fuselages and automobile chassis. Longerons are used in conjunction with stringers to form structural frameworks.

Mountain Air Cargo

Mountain Air Cargo (MAC) is an American cargo airline based in Denver, North Carolina. It is a major contract carrier for FedEx Express, operating in the eastern United States and the Caribbean region. Previous turboprop operations in South America have been discontinued by FedEx, which now operates jet aircraft in that area. MAC is one of the largest feeder airlines in the United States. Its main maintenance facility is at Kinston Regional Jetport. All of the ATR and C208 aircraft operated by Mountain Air are owned by FedEx Express, and are operated by MAC on a "dry lease" basis.

NACA cowling

The NACA cowling is a type of aerodynamic fairing used to streamline radial engines for use on airplanes and developed by the National Advisory Committee for Aeronautics in 1927. It was a major advance in aerodynamic drag reduction, and paid for its development and installation costs many times over due to the gains in fuel efficiency that it enabled.

Passenger service unit

A passenger service unit (PSU) is an aircraft component situated above each row in the overhead panel above the passenger seats in the cabin of airliners. Among other things, a PSU contains reading lights, loudspeakers, illuminated signs, buttons to call for assistance, air condition vents, and automatically deployed oxygen masks.

Preflight checklist

In aviation, a preflight checklist is a list of tasks that should be performed by pilots and aircrew prior to takeoff. Its purpose is to improve flight safety by ensuring that no important tasks are forgotten. Failure to correctly conduct a preflight check using a checklist is a major contributing factor to aircraft accidents.Following a checklist would have shown that the gust lock was engaged on the Gulfstream IV crash on May 31, 2014. The National Transportation Safety Board downloaded data from the aircraft's recorder and found it was a habit: 98% of the previous 175 takeoffs were made with incomplete flight-control checks. The National Business Aviation Association analyzed 143,756 flights in 2013-2015 by 379 business aircraft and only partial flight-control checks were done before 15.6% of the takeoffs and no checks at all on 2.03% of the flights.

Rib (aeronautics)

In an aircraft, ribs are forming elements of the structure of a wing, especially in traditional construction.

By analogy with the anatomical definition of "rib", the ribs attach to the main spar, and by being repeated at frequent intervals, form a skeletal shape for the wing. Usually ribs incorporate the airfoil shape of the wing, and the skin adopts this shape when stretched over the ribs.

Stressed skin

In mechanical engineering, stressed skin is a type of rigid construction, intermediate between monocoque and a rigid frame with a non-loaded covering. A stressed skin structure has its compression-taking elements localized and its tension-taking elements distributed. Typically, the main frame has rectangular structure and is triangulated by the covering.

Townend ring

A Townend ring is a narrow-chord cowling ring fitted around the cylinders of an aircraft radial engine to reduce drag and improve cooling.

Trailing edge

The trailing edge of an aerodynamic surface such as a wing is its rear edge, where the airflow separated by the leading edge rejoins. Essential flight control surfaces are attached here to control the direction of the departing air flow, and exert a controlling force on the aircraft. Such control surfaces include ailerons on the wings for roll control, elevators on the tailplane controlling pitch, and the rudder on the fin controlling yaw. Elevators and ailerons may be combined as elevons on tailless aircraft.

The shape of the trailing edge is of prime importance in the aerodynamic function of any aerodynamic surface. George Batchelor has written about:

“ ... the remarkable controlling influence exerted by the sharp trailing edge of an aerofoil on the circulation.”Other sharp-edged surfaces that are attached to the trailing edges of wings or control surfaces include:

On control surfaces:trim tabs

servo tabs

anti-servo tabsOther surfaces:flapsOther equipment that may be attached to the trailing edges of wings include:

anti-shock bodies

static dischargers

Wing root

The wing root is the part of the wing on a fixed-wing aircraft or winged-spaceship that is closest to the fuselage. On a simple monoplane configuration, this is usually easy to identify. On parasol wing or multiple boom aircraft, the wing may not have a clear root area.Wing roots usually bear the highest bending forces in flight and during landing, and they often have fairings (often named "wing fillets") to reduce interference drag between the wing and the fuselage.The opposite end of a wing from the wing root is the wing tip.

Yaw damper

A yaw damper is a device used on many aircraft (usually jets and turboprops) to damp (reduce) the rolling and yawing oscillations known as the Dutch roll mode. It consists of yaw-rate sensors and a processor that provides a signal to an actuator connected to the rudder. The use of a yaw damper helps provide a better ride for passengers by preventing the uncomfortable yawing and rolling oscillation. On some aircraft it is mandatory for the yaw damper to be operational at all times during flight above a specified altitude.

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