Aeronautics and astronautics – Aircraft structure – Details
Patent
1994-03-21
1996-05-21
Barefoot, Galen L.
Aeronautics and astronautics
Aircraft structure
Details
29225669, 292DIG49, 292DIG65, B64C 114
Patent
active
055182062
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to structural assemblies having closure parts one or each of which is displaceable relatively to the other between closed and open dispositions and which are locked in the closed disposition by a locking mechanism and is particularly although not exclusively concerned with a fan cowl door assemblies for aero engine nacelles.
Aero engine nacelles are commonly provided with right hand and left hand fan cowl doors which have upper edges which are hinged along the upper part of the nacelle and which have lower edges which are held in engagement with each other at the base of the nacelle by latch mechanisms arranged at spaced positions along the lower edges of the doors.
It has been found that where toggle lever operated latch mechanisms are used for locking together the bottom edges of fan cowl doors the latching operation can be overlooked or ineffectively carried out. For example, the toggle lever fitted on the lower edge of one of the fan cowl doors can be operated through its full throw without engagement with the cooperating part of the latch mechanism on the lower edge of the other door or indeed not operated at all. The default is however not readily observed by ground personnel as the weight distribution of the fan cowl doors which are hinged at their upper edges brings the bottom edges of the doors into engagement with each other and the latch mechanisms are so constructed that the toggle lever lies flush with the surface of the mechanism whether or not the latching operation has been carried out or carried out effectively.
Closure defaults as above described have led to fan cowl doors being lost in flight and although no injuries have been reported from lost cowl door incidents aircraft and property on the ground have been damaged.
A review by the Federal Aviation Authority (FAA) of a number of inflight incidents where engine cowl doors have been lost has revealed that the greatest cause of such incidents has been improper latching of the latching mechanisms at the lower edges of the doors or a complete failure to operate the latch mechanisms.
As a result of the review, the FAA require that for any nacelle cowling, the opening of which could preclude continued safe flight and landing there must be provision for direct visual inspection of the latching mechanism to verify that the cowl doors are fully closed and locked. Such provision must be discernable under operational lighting conditions by appropriate crew members, if necessary using a flash light or the equivalent lighting source.
It is an object of the present invention to provide means whereby a default in the closure of the fan cowl doors of an aero engine nacelle can readily be detected by ground personnel.
According to a first aspect of the present invention there is provided a structural assembly comprising first and second closure parts displaceable relative one another between a closed disposition in which a closing edge of one closure part is generally aligned with a closing edge of the other closure part to provide a rear side of the closure parts closed off from a front side of the closure parts and open dispositions in which the closing edge of one closure part is spaced from the closing edge of the other closure part, a locking mechanism for locking the closure parts in the closed disposition and a default indicating device comprising a projection element which is movable against biasing means to the rear side of the closure parts, and is released when the closure parts move to a predetermined open disposition wherein a gap is formed between the closing edges of the closure parts and which moves in response to the biasing means to a projecting position in which it projects through the cap between the closure parts to the front side to provide on the front side of the closure parts a visual warning that the closure parts are not in the closed disposition. The default indicating device may be operable independently of the locking mechanism.
In a first embodiment of the invention hereinafter to be describe
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patent: 4150802 (1979-04-01), Evelyn et al.
patent: 4265474 (1981-05-01), Poe
patent: 4498823 (1985-02-01), Trautman
patent: 4613099 (1986-09-01), Smith et al.
patent: 4679750 (1987-07-01), Burnans
patent: 4905892 (1990-03-01), Fischer
patent: 5011200 (1991-04-01), Glancy et al.
Arnold Michael J.
Hall Brian J.
Johnson Kenneth H.
Barefoot Galen L.
Short Brothers PLC
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