| Description | Date | Identifier | |
| Letter from Bosch agreeing to test a 744 plug and submit suitable samples in return. | 25th Jun 1934 | Box 58 \ 2 Scan142 | |
| Goshawk I type test for sparking plugs, detailing electrode erosion measurements. | 11th Jul 1934 | Box 58 \ 2 Scan143 | |
| Spark plug wear measurements by engine position and plug type. | 11th Jul 1934 | Box 58 \ 2 Scan144 | |
| Summary of research on the three phases of spark plug discharge connected to a magneto. | 1st Aug 1934 | Box 58 \ 2 Scan145 | |
| Report from the Royal Aircraft Establishment on tests of B.B. Bologna sparking plugs type S.6. | 1st Sep 1934 | Box 58 \ 2 Scan146 | |
| Detailed description and weight comparison of a sparking plug. | 1st Sep 1934 | Box 58 \ 2 Scan147 | |
| Report page detailing the dimensions and test results for a plug, including a comparison with Bologna plug dimensions. | 1st Sep 1934 | Box 58 \ 2 Scan148 | |
| Results of gas leakage, gland tightness, and external flash over tests on a set of six plugs. | 1st Sep 1934 | Box 58 \ 2 Scan149 | |
| Report page detailing a series of spark plug tests, including flash over, dielectric strength, air pressure, and in-flight engine tests. | 1st Sep 1934 | Box 58 \ 2 Scan150 | |
| Report page detailing the satisfactory condition of spark plugs after 10 hours of flight tests. | 11th Sep 1934 | Box 58 \ 2 Scan151 | |
| Diagram of a sparking plug, type Bologna S.6, with component labels and specifications. | 11th Sep 1934 | Box 58 \ 2 Scan152 | |
| Inter-organization letter from Cadillac discussing car antennas and ignition suppressors. | 17th Sep 1934 | Box 58 \ 2 Scan153 | |
| Requesting the stelliting of 21 centre electrodes for sparking plug trials. | 2nd Oct 1934 | Box 58 \ 2 Scan154 | |
| Order for various types of aero sparking plugs. | 3rd Oct 1934 | Box 58 \ 2 Scan155 | |
| The supply of Lodge and K.L.G. sparking plugs for a Goshawk 35 fuel economy test. | 11th Oct 1934 | Box 58 \ 2 Scan156 | |
| Translated research paper on the working of sparking plugs by R. Anthouard. | 11th Oct 1934 | Box 58 \ 2 Scan157 | |
| Analysis of spark ignition phenomena, including tension, pressure effects, and wire armouring. | 11th Oct 1934 | Box 58 \ 2 Scan158 | |
| The phases of a spark, parasites in wireless reception, and the construction of plugs and magnetos. | 1st Mar 1934 | Box 58 \ 2 Scan159 | |
| Technical studies on magneto discharge, spark plug operation, and thermal control systems. | 1st Mar 1934 | Box 58 \ 2 Scan160 | |
| Page from the French publication 'L'Aéronautique' discussing spark plug oscillograph recordings. | 1st Mar 1934 | Box 58 \ 2 Scan161 | |
| Letter to Cadillac discussing sparking plug suppression, idling performance, and experiments with hotter plugs and shielded systems. | 26th Oct 1934 | Box 58 \ 2 Scan162 | |
| Letter from an Electrical Engineer requesting information on the performance of dynamos on La Salle and Cadillac cars. | 30th Oct 1934 | Box 58 \ 2 Scan163 | |
| Confirming the return of faulty Bentley sparking plugs for remarks. | 30th Oct 1934 | Box 58 \ 2 Scan164 | |
| Outlining the procedure for submitting sparking plugs for servicing and overhaul. | 12th Dec 1934 | Box 58 \ 2 Scan165 | |
| Tests on sparking plugs fitted with electrodes coated with palladium, platinum and rhodium to reduce erosion caused by spark discharge. | 1st Nov 1933 | Box 58 \ 2 Scan166 | |
| The erosion of different coated spark plug electrodes during tests in a Kestrel engine. | 1st Nov 1933 | Box 58 \ 2 Scan167 | |
| Tests on standard, palladium, and rhodium coated K.L.G. Type VII plugs in a 'Pegasus' engine. | 1st Nov 1933 | Box 58 \ 2 Scan168 | |
| Conclusions on the effectiveness of platinum, palladium, or rhodium coatings on nickel electrodes to delay erosion. | 1st Nov 1933 | Box 58 \ 2 Scan169 | |
| Photographic comparison of standard, palladium coated, and rhodium coated K.L.G. V.II spark plug electrodes. | 6th Dec 1933 | Box 58 \ 2 Scan170 | |
| Study of spark plug electrode erosion, comparing coated vs. uncoated nickel and different noble metal coatings in a Kestrel engine. | 6th Dec 1933 | Box 58 \ 2 Scan171 | |
| Confirming the arrangement for a pressure rig for sparking plug tests. | 30th Nov 1934 | Box 58 \ 2 Scan172 | |
| Order for K.L.G. and Lodge spark plugs. | 17th Dec 1934 | Box 58 \ 2 Scan173 | |
| Solutions for improving the cooling and reliability of aero engine sparking plugs. | 26th Jan 1935 | Box 58 \ 2 Scan174 | |
| Use of spark plugs in aluminium and the possibility of adding an inter-cooler. | 26th Jan 1935 | Box 58 \ 2 Scan175 | |
| Internal order request for two types of sparking plugs from two different suppliers. | 4th Feb 1935 | Box 58 \ 2 Scan176 | |
| Clarifying which aero sparking plugs have official Air Ministry approval for flight purposes. | 4th Feb 1935 | Box 58 \ 2 Scan177 | |
| Order for a Dewrance pressure gauge for a sparking plug test rig. | 1st Mar 1935 | Box 58 \ 2 Scan178 | |
| Packing note from Lissen Limited for 12 spark plugs sent for testing purposes. | 3rd Apr 1938 | Box 58 \ 2 Scan179 | |
| Urgent order request for two types of aero sparking plugs. | 5th Mar 1935 | Box 58 \ 2 Scan180 | |
| To place an urgent order for two different types of spark plugs from suppliers Lodge and K.L.G. | 30th Mar 1935 | Box 58 \ 2 Scan181 | |
| List of experimental plugs for testing, detailing their specific types and characteristics. | 1st Apr 1935 | Box 58 \ 2 Scan182 | |
| Letter from Lissen Ltd. offering a new range of mica sparking plugs and sending samples for testing. | 4th Apr 1935 | Box 58 \ 2 Scan183 | |
| Continuation sheet from Lissen Limited proposing collaboration on a special spark plug for 1935/6 models. | 4th Apr 1935 | Box 58 \ 2 Scan184 | |
| Advertising leaflet for Lissen Mica Plugs, detailing their benefits and providing maintenance advice. | 4th Apr 1935 | Box 58 \ 2 Scan185 | |
| Advertisement and recommendation list for Lissen chromium-plated mica plugs, including models for various motor cars and motorcycles. | 9th Apr 1935 | Box 58 \ 2 Scan186 | |
| Difficulty of fitting screened plugs on Kestrel X, XI, and XII engines. | 9th Apr 1935 | Box 58 \ 2 Scan187 | |
| Order for various types of aero sparking plugs. | 16th Apr 1935 | Box 58 \ 2 Scan188 | |
| The flight approval of V9/1B sparking plugs for 6 lbs boost engines. | 25th Apr 1935 | Box 58 \ 2 Scan189 | |
| Misfiring Bentley sparking plugs at high engine revs when hot. | 30th Apr 1935 | Box 58 \ 2 Scan190 | |
| The electrical testing of Bentley sparking plugs and follow-up actions. | 8th May 1935 | Box 58 \ 2 Scan191 | |
| Typed memo proposing a meeting to discuss sparking plug failures. | 9th May 1935 | Box 58 \ 2 Scan192 | |
| Request to order a Coddington magnifier for analysing aero sparking plug failures. | 10th May 1935 | Box 58 \ 2 Scan193 | |
| Approved spark plugs for Kestrel engines with take-off boost. | 13th May 1935 | Box 58 \ 2 Scan194 | |
| Modifications for the use of screened plugs in Kestrel engines. | 2nd May 1935 | Box 58 \ 2 Scan195 | |
| Internal order request for a Coddington Magnifier for analysing plug failures. | 5th May 1935 | Box 58 \ 2 Scan196 | |
| Internal memorandum discussing the suitability and failure of various ignition plugs for 'Kestrel' engines under different boost conditions. | 15th May 1935 | Box 58 \ 2 Scan197 | |
| The testing of Lodge and K.L.G. plugs for 'Kestrel' engines with take-off boost. | 15th May 1935 | Box 58 \ 2 Scan198 | |
| Requesting tests on the ignition plug position in a ramp head cylinder to observe effects on power, detonation, and plug temperatures. | 16th May 1935 | Box 58 \ 2 Scan199 | |
| The repair or replacement of sparking plugs removed from various chassis. | 17th May 1935 | Box 58 \ 2 Scan200 | |
| Letter from the Air Ministry regarding comparative in-flight trials of spark plugs for Kestrel V and VI engines. | 17th May 1935 | Box 58 \ 2 Scan201 | |
| Confirming the return of plugs that passed testing. | 20th May 1935 | Box 58 \ 2 Scan202 | |
| The unsuitability of Lissen sparking plugs for the 20/25 engine due to over-oiling. | 28th May 1935 | Box 58 \ 2 Scan203 | |
| Proposing a new, centralised maintenance routine for sparking plugs to reduce unnecessary scrap. | 7th Jun 1935 | Box 58 \ 2 Scan204 | |
| Letter from Ethyl Export Corporation regarding the return of a blueprint and a request for K.L.G. plug sections. | 15th Jun 1935 | Box 58 \ 2 Scan205 | |
| Issues with sparking plugs and proposing the centralization of this job. | 24th Jun 1935 | Box 58 \ 2 Scan206 | |
| Legal risks of patent infringement concerning the use of Lodge Screened Aero Plugs. | 1st Jul 1935 | Box 58 \ 2 Scan207 | |
| Letter to Lodge Plugs Ltd. regarding patent infringement concerns over screened plugs. | 2nd Jul 1935 | Box 58 \ 2 Scan208 | |
| Request to make plates to accommodate aero sparking plugs as per drawings EL169 and 170. | 11th Jul 1935 | Box 58 \ 2 Scan209 | |
| Letter from a test pilot and aeronautical consultant regarding an enquiry for Detonindex valves and suggesting the testing of B.G. Plugs. | 17th Jul 1935 | Box 58 \ 2 Scan210 | |
| Decision to fit specific K.L.G. and Lodge sparking plugs for a Kestrep Exp.5 type-test. | 19th Jul 1935 | Box 58 \ 2 Scan211 | |
| Letter declining further testing of a B.G. plug and screen on Kestrel engines. | 19th Jul 1935 | Box 58 \ 2 Scan212 | |
| Correspondence regarding a patent for improvements in sparking plugs. | 25th Jul 1935 | Box 58 \ 2 Scan213 | |
| Letter from G. H. J. W. Hewitson proposing a new ignition system design for aeroplane engines. | 25th Jul 1935 | Box 58 \ 2 Scan214 | |
| Requesting a drawing for G.E. & J.W. Hewitson sparking plugs. | 6th Aug 1935 | Box 58 \ 2 Scan215 | |
| The dispatch of a drawing for Hewitson sparking plugs. | 7th Aug 1935 | Box 58 \ 2 Scan216 | |
| Use of new types of sparking plugs for a Kestrel V type test engine. | 7th Aug 1935 | Box 58 \ 2 Scan217 | |
| Letter confirming receipt of 100 K.L.G. booklets from Messrs. Hunt, Barnard & Co. Ltd. | 16th Aug 1935 | Box 58 \ 2 Scan218 | |
| Investigation into the cause of Bentley sparking plug misfiring, theorized to be caused by lead oxide deposits. | 16th Aug 1935 | Box 58 \ 2 Scan219 | |
| Investigation into misfiring issues with the 850 plug. | 16th Aug 1935 | Box 58 \ 2 Scan220 | |
| Requesting drawings and specifications for a Sparking Plug Test Rig for the Air Ministry. | 7th Aug 1935 | Box 58 \ 2 Scan221 | |
| Internal request to order two dozen type 850 sparking plugs. | 15th Aug 1935 | Box 58 \ 2 Scan222 | |
| Private memorandum regarding sparking plug trouble and obsolete parts for Kestrel S engines at Pembroke Dock. | 19th Aug 1935 | Box 58 \ 2 Scan223 | |
| Private memo regarding sparking plugs and fuel requirements for Kestrel X engines. | 19th Aug 1935 | Box 58 \ 2 Scan224 | |
| Sparking plug trouble at Pembroke Dock, focusing on obsolete and incorrect plug types fitted to 'Singapore' engines. | 20th Aug 1935 | Box 58 \ 2 Scan225 | |
| Patent for improvements in sparking plugs from G.E. & J.E. Hewitson. | 26th Aug 1935 | Box 58 \ 2 Scan226 | |
| The conversion of sparking plugs for Merlin engines. | 26th Aug 1935 | Box 58 \ 2 Scan227 | |
| Evaluating the suitability of Hewitson Sparking Plugs for use in aero engines. | 28th Aug 1935 | Box 58 \ 2 Scan228 | |
| Requesting to post one framed sparking plug drawing. | 28th Aug 1935 | Box 58 \ 2 Scan229 | |
| Hewitson Sparking Plugs and the return of a provisional specification. | 29th Aug 1935 | Box 58 \ 2 Scan230 | |
| Cover note for the patent specification of the Hewitson plug. | 31th Aug 1935 | Box 58 \ 2 Scan231 | |
| The unavailability of 850 plugs and advising to arrange a small stock for replacement work. | 2nd Sep 1935 | Box 58 \ 2 Scan232 | |
| Proposal to test two types of experimental sparking plugs during a 50-hour fuel economy test. | 2nd Sep 1935 | Box 58 \ 2 Scan233 | |
| Letter to the Royal Aircraft Establishment requesting the release of blueprints. | 6th Sep 1935 | Box 58 \ 2 Scan234 | |
| Secret memo regarding designs for Spectre sparking plug spanners and terminals. | 6th Sep 1935 | Box 58 \ 2 Scan235 | |
| Sending used K.L.G. and Lodge spark plugs back to their makers for examination after a 100-hour type-test. | 10th Sep 1935 | Box 58 \ 2 Scan236 | |
| Requesting a substantial Yale lock for the experimental sparking plug stock cupboard due to pilfering. | 13th Sep 1935 | Box 58 \ 2 Scan237 | |
| Request to manufacture two external plugs for an extra battery on a Horsley aircraft fitted with a Merlin C engine. | 17th Sep 1935 | Box 58 \ 2 Scan238 | |
| Letter reporting on the failure of Lodge and K.L.G. sparking plugs during a test on a Merlin C.3 engine. | 20th Sep 1935 | Box 58 \ 2 Scan239 | |
| Recommendation against using a spring clip to secure a plug in a spanner, suggesting engagement with the plug's screw thread instead. | 2nd Oct 1935 | Box 58 \ 2 Scan240 | |
| Letter from the Air Ministry concerning sparking plugs for the Merlin engine. | 2nd Oct 1935 | Box 58 \ 2 Scan241 | |
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