230 AIRCRAFT ENGINEERIN.G September, 1931 Instruction s to Aircraft Owners and Ground Engineers Regardin g Essential Modifications No . 33 of the year 1931 27/64 in. This latter operation is one demanding Th e bracing lugs should, therefore, be cut off jus t below the bend line t o eliminate any possibility extrem e care in order to avoid damage t o th e threads Several engine failures have been caused by the of fouling between the aileron controls in this region. in the rod. The new stud should be a tight fit in carburetto r float mechanism breaking down, due The old Part No. 722 has now been superseded by th e rod throughout its length. The stud should be to failure of the locking wire in the needle valve Par t No. 7. screwed down until the bottom of the hole for the toggle pins. split pin is not less than ⅞ in. from the shoulder of Th e ball joint, aileron lever, and connecting rod These failures are due to the use of the locking th e rod, and the top of the hole no t more than 1 in., hav e been re-designed, and must be replaced by wires more then once. th e hole lying parallel with the axis of the bore of new parts which are obtainable from Messrs. Whenever a locking wire is withdrawn during th e rod. Sparta n Aircraft Ltd., East Cowes. The new part dismantling it should be discarded and replaced When the stud is in position, it should be drilled number s are given below :— b y new material. Par t No. 110A/C, 110C/C, A.I.E-8, A.I.E. for the locking pin, which is made from a short Jun e 4, 1931. (Slotted), AGS. 166/3— 1 of each. 1297C/D, 1300 length of No. 10 S.W.G. mild steel wire. The pin D/C— 2 of each. mus t be of such a length tha t it is slightly counter No . 34 of the year 1931 sunk when in position, the edge of the pin-hole in The above modification must be incorporated in Th e attention of aircraft owners and ground th e connecting rod being slightly pecned over to all aircraft concerned within one month of the date engineers is directed to the special care necessary retain the pin in position. of this Notice in order that Certificates of Air when tightening the nuts on master connecting worthiness shall remain valid or may be renewed. Cancellation.—Notice to Aircraft Owners and rod studs on Napier " Lion " engines. Ground Engineers No. 28 of the year 1930 is hereby Jul y 9, 1931. These nuts must be sufficiently tight to hold the cancelled. bearing cap securely under running conditions, No . 38 of the year 1931 Jun e 8, 1931. bu t not so tight as to cause stretching of the studs. Modification No.H.M.109 —Auxiliary Cylinder To ensure this correct tension, the engine makers Lubrication in Mark I Cirrus-Hermes engines. No . 35 of the year 1931 employ a spring-loaded spanner set to give a maxi To ensure adequate cylinder lubrication and Notice No. 35 contains additions to the lists of mu m loading of 945 in./lb . (135 lb. at 7 in. radius). to assist in the cooling and general running condi designs of airscrews approved for various type It is very desirable to use a spanner such as tions, a 1/32-in. diameter oil hole is now drilled in of civil aircraft published in Notices Nos. 3-15. tha t referred to above, but when this is four of the plugs located in the crank webs, as [See AIRCRAFT ENGINEERING, March, 1931, p. 60.] not available a box spanner and a tommy bar can shown on drawing C.A.47. be used, the latter not to exceed 7½ in., measured Crankshaft oil retainers and piston-scraper rings No . 36 of the year 1931 from the centre of the box spanner, and the total as listed below are also fitted :— Cases of failure of the main plane ribs of Avro length of the bar not to be in excess of 8⅜ in. The Part No. Description. No. per Avian aircraft have occurred. The failures occurred nut s must be tightened by applying a steady engine. on ribs constructed with flanges¼ in. wide by 3/16 in . pressure to the spanner. C.453 Crankshaft oil retainer 4 deep and not fitted with metal saddle clips at the If any correction is necessary in order to obtain C.371. A. Piston-scraper ring 4 spars . alignmen t between the split pin hole in the stud and This modification should be incorporated in Th e wings of all Avian aircraft are, therefore, to th e castellation of the nut, this must be effected by engines during the next overhaul. be examined forthwith, and those fitted with ribs removing the nut and facing off the bottom face, Fittin g of the parts concerned is fully of th e type described above are not to be flown until care being taken that a true surface is obtained explained on drawing C.A.47, referred to above. a full examination of all ribs has been made. The between this face of the nut and the bearing cap. Modification No. H.M. 112—Exhaust Valves. typ e of rib involved can be identified by measure (Note : 0.010 in. removed from the face of the nut A strengthened exhaust valve of modified men t of the rib flange at the rear spar and also by will allow it to be tightened down 1/6th of a turn). form to Part No. C. 160 A has been introduced by th e absence of the metal saddle clips mentioned A special tool, Part No. 48263, for facing the nuts modification No. H.M.I 12, and it is desirable that above . is to be used exclusively for this operation ; on no valves of this type be fitted to engines a t the first accoun t are the nuts to be filed. If in the process Wings fitted with the ribs above described are to convenient opportunity. In any case they should of facing the nut too much metal is removed, so be completely opened up and examined internally be fitted during the next top overhaul. tha t the split pin slot goes slightly past its proper for soundness of all ribs, and in particular the Th e number of the engine for which parts position, the nut must on no account be slackened security of all glued joints, including attachment s of ar e required must be stated. back to enable the split pin to be fitted ; either rib flanges to the spars and to the trailing edge. When the modifications referred to in the above anothe r nut must be used, or the nut must be faced Unless this examination shows the condition of all paragraph s have been incorporated, the name-plate down still more until the next slot comes into the ribs to be completely satisfactory, no further flying attache d to the engine should be marked accord correct position. Any nuts having slots which do ma y be undertaken prior to modification of all ribs ingly, i.e., " Engine No. 000 " should be amended no t register correctly with the hole in the stud in accordance with Messrs. A. V. Roe's drawings t o read " Engine No. 000/Mod. Mark II." F . 1788 and F . 1789. If this examination shows all should be rejected. Th e data sheet and title-page of the engine log ribs to be sound, further flying may be undertaken, Each split pin must closely fit the hole in the book should also be suitably amended. bu t only within the Normal Category. In no connecting rod stud. When the nut is correctly Modification No. H.M. 109 has already been circumstances may acrobatic flying be undertaken tightened there should be no clearance between the carried out on a few Mk. I engines and the marking until the modified ribs mentioned above have been pin and the slot of the nut as would permit of any " M.I " has been stamped on the crankcase adjacent incorporated . slackening of the nut. Split pins should not be to the name-plate, on engines so modified. When All Avian aircraft fitted with the ribs above more than ⅞ in. long in the parallel portion, and modification No. H.M. 112 ha s also been incorporated described are to be modified in accordance with when fitted the ends are to be opened and turned in these engines, they should have the mark " M.I " Messrs. A. V. Roe's drawings F. 1788 and F. 1789 over the nut so that no movement of the pin can obliterate d and be re-marked as described in before acrobatic flying may be undertaken, and in occur. paragrap h (3). an y case before July 31, 1931. Stud s for the " Lion " master connecting rod are Exhaust Manifold and Engine Cowling. Owners will, in the near future, receive com now made from steel to B.E.S.A. Specification S.65. Aircraft owners and ground engineers are munications" from Messrs. A. V. Roe, making Whe n any replacements are necessary, studs of this advised that to ensure satisfactory functioning of arrangement s for the above-mentioned modifica material , which arc identifiable by a saw-cut across th e Cirrus-Hermes engine, the cylinder cowling tions where necessary. If notification of such th e end, should be used. At the engine makers, an d exhaust manifold should conform to th e require arrangement s is not received, owners should them these studs are driven with a spring-loaded spanner ment s of designs prepared by the makers. selves communicate with Messrs. A. V. Roe. set to give a maximum loading of 840 in./lb. Th e following is a list of drawings from which |un e 25, 1931. (120 lb. at 7 in. radius). Alternatively, if a spring- th e necessary particulars can be obtained :— loaded spanner is not available, the box spanner Closed typ e engine cowling. Drawing No. C.A.42. No . 37 of the year 1931. and tommy bar referred to above may be used. Open ,, ,, ,, ,, ,, C.A.43. To remove a stud, first drill out the locking pin, Cases have occurred with Spartan 2- an d 3-seater Exhaus t manifold. ,, ,, C.353.C using a ⅛in. drill. Care is necessary during this aircraft, of the aileron controls on the underside of Owing to the possibility of engine cowlings operation as there is a risk of th e drill running out to th e fuselage, at the ball joint fitting, fouling the being damaged or distorted when removed during one side and breaking. The pin having been drilled ben t down bracing lugs (Part No. 722) at the inner overhaul , they should be examined and corrected if out, the stud may be very carefully withdrawn. ends of the rear spar on the underside of the lower necessary, as otherwise the cooling of the cylinders Should there be any tendency of the stud to seize planes. These bracing lugs, which form part of the ma y be seriously affected. in the rod during withdrawal, the operation should hinge plate fitting, are redundan t on th e underside of Copies of the drawings referred to in this Notice, be stopped before the threads in the rod suffer th e lower planes, having been originally intended to together with modified engine parts, can be obtained damage , and the stud must then be drilled out, facilitate interchangeability of the top and bottom from the engine makers, using a drill of the correct tapping size, namely planes . July 11, 1931.
Aircraft Engineering and Aerospace Technology – Emerald Publishing
Published: Sep 1, 1931
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