Inspection Panels By Arthur W. ./. G. Ord-Hume "Miraclor", Rose Mead, Lake, Sandown, Isle of Wight, England

OWEVER »vell-designed or well-built an airplane may H be, it must periodically require maintenance of one sort or another. Too often, maintenance is considered to embrace purely physical work on the machine but, in actual fact, inspection is as much a part of maintenance as is total disassembly. Regular visual inspection, lubrication where necessary and other occasional servicing are vital aids towards prolonging the useful life of any machine. The airplane, amateur-built or otherwise, is no exception to this rule. To aid aircraft inspection and maintenance it is usual practice to arrange a suitable part of the outer covering adjacent to the portions of the structure requiring periodic checking to be removable. These parts are called inspection panels, hatches or doors. In their simplest form, they comprise a celluloid frame doped on to the fabric and covered with a tear-off patch. Other types include hinged doors in ply-covered structures or, especially in large or high-speed aircraft, plates secured with quick-release studs or small bolts. The amateur airplane builder is often tempted to dispense with making provision for inspection hatches and this can to a certain extent be understood when one realizes that to remove a tear-off fabric patch from a celluloid frame destroys the surrounding paint scheme and a removable panel secured with catches or screws can spoil both airflow and appearance. Some manufacturers have employed the celluloid ring technique, the fabric being cut out of the center in

Fig. 1 — The woodwork

surrounding

the

inspection hatch as viewed from the outside.

Fig. 2—The woodwork surrounding the inspection hatch as seen from the inside. Note how the member between the ribs (upper center of picture) is of small cross section stiffened by a one-inch wide plywood web. Actual member is only VA in. by % in. spruce.

Fig. 3—The inspection hatch is shown here in position.

It should be removed before fabric-covering and re-fitted before final spray finish is applied.

Fig. 4—Hatch is seen here installed in the vertical stabilizer of wooden four-place Gemini aircraft. Engineer's hand shows comparative size. SPORT AVIATION

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manufacture and an alloy disc with a spring clip used to close the hole. However, this is unsightly and is not

really suitable for ply-covered structures. An aircraft built without facilities for inspecting the inside of closed components or internal moving fittings

Fig. 7—The same type of catch is seen here applied to a metal door in the side of the Gemini engine bearer.

Fig. 5—Finger pressure releases catch by drawing back wire spring clip.

must sooner or later be cut open with subsequent spoiling of the finish and needless extra work. It is thus vital that the constructor should incorporate adequate inspection facilities when he builds his aircraft. A particularly neat type of inspection hatch was designed in England by Miles Aircraft Limited, now part of the Beagle group. This style of hatch is in use on all Miles aircraft and variants are used on high-speed aircraft. It has the advantage of being easy to make and to install and is perfectly flush with the surface as well as being both neat and inconspicuous. It is readily opened by the pressure of one finger on the catch. The illustrations show the manufacture of the hatch

together with typical installations for both fabric-covered

Fig. 6—The door is seen here in the open position allowing access to control push rod.

structures and plywood-skinned assemblies. The hatch should be arranged to lock flush with the surrounding surface in the closed position and this is easily achieved by adjusting the bend in the spring clip. Wherever possible, panels should be sited on the undersurface of wings and always with the hinge line either facing the line of flight or to one side, never at the rear. These hatches or doors may be made in any shape or

size providing that the door cannot distort in flight.

TYPICAL FRAMING WITH

LONG-GRAINED PLY STRIP AS AT OTHER EDGE

DIRECTION OF FLIGHT

GUSSETS ON UNDERSIDE

MEMBERS ARE "i" x V4" OR

!-i" x V

PLY SKIN

INNER PLY

DOUBLER PROVIDES

LAND FOR DOOR IN

CLOSED POSITION

NOTCH CROSS MEMBER UNDER CAPSTRIP OR

GUSSET OR

LONG-GRAINED PLY STRIP TO STIFFEN WICHEVER CROSS MIMBER MOST CONVENIENT

FIG 10 A TYPICAL INSTALLATION IN A FABRIC-COVERED SURFACE NOTE THE USE OF LIGHT.SECTION SPRUCE STIFFENED WITH STRIPS OF LONG-GRAINED PLYWOOD

DOUBLER LET INTO

SUPPORTING

MEMBERS FLUSH WITH SURFACE OUTER PLY SKIN GLUED ON TOP

It

DECEMBER 1962

FIG 9

AN EXAMPLE OF THE INSTALLATION

OF AN INSPECTION DOOR

HINGE FLUSH RIVETTEDTO

FINGER WIRE LOCK HINGE DOUBLE R

THIS EDGE

SPRING

GUIDE ACCESS HOLE TOFACILITATE CLOSING RIVET

DETAIL SHOWING UNDERSIDE OF CATCH IN HALF OPEN POSITION

FIG. 8 VIEW ON UNDERSIDE OF HATCH SHOWING CATCH IN CLOSED POSITION

INSPECTION HATCH DETA lit CONSTRUCTION

MAKE: FROM ALLOY SHEET •O48 THICK AND HARD STEEL WIRE

T

RIVETS FLUSH ON

FACE

X

^,V

INSPECTION PANELS . . . (Continued from preceding page)

Doors greater than about 6 in. in width should be fitted with two catches.

The intelligent siting of this type of door can render visual inspection very easy and, once installed, cannot get lost or go wrong.

FAA NEWS FAA TO SURVEY CERTIFICATED MAINTENANCE AIRMEN

A survey of certificated maintenance airmen will be conducted by the Federal Aviation Agency to find out immediately how many are active and what types of work they do. George C. Prill, Director of the FAA's Flight Standards Service, said the data is needed to evaluate and plan the maintenance airman certification and surveillance program. He pointed out that this program has remained relatively unchanged for more than 30 years, and probably should be realigned with the responsibilities of maintaining modern complex aircraft. The information sought by the survey will be similar to that which will be obtained from the agency's proposed renewal program for all airmen certificates. However, since full data from this program will not be available until July, 1965, all maintenance airmen are asked to participate in the present survey. The survey, which will run from Nov. 1 through Nov.

30, is directed at certificated mechanics, repairmen and authorized inspectors in all segments of the aviation community. This includes the airlines, business flying, approved repair stations, fixed base operators, aircraft manufacturers, mechanic schools, as well as certificate holders

not currently working in aircraft maintenance. Military

personnel holding civil maintenance airmen certificates also are asked to participate. To date, more than 119,000 maintenance airmen certificates with ratings have been issued. However, little information is available on the number of active certificate holders, industry utilization of these airmen, the types of equipment on which they work, or their activities and duties. The survey will develop this data. The questionnaire being used in the study consists of 12 questions which require a minimum of writing. In addition to the name and address, eight of the questions can be answered by merely circling an appropriate number, and two may be completed by inserting a date and

number. Questionnaire forms may be obtained from any FAA district or international field office. In addition, forms will be given wide distribution throughout the aviation industry and should be available at most aircraft maintenance facilities such as airline shops, repair stations and fixed base operators. The FAA requests that the forms be completed and

returned immediately. No postage is necessary since each questionnaire form bears a franked return address. SPORT AVIATION

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