Luscombe Parts Manuals and Firewalls Article

that same parts manual at items 23-30, figure 3, page 20; ALSO describes and discusses alternate firewall configurations and various part numbers for those configurations. We will discuss these different firewall part numbers. This discussion will establish that a variety of different part numbers are legitimate, “CAA or FAA approved” configuration part numbers that can be legally installed into Luscombes. The CAA/FAA approved data / drawings described by CFR § 21.31, (a), were also required by CAR 4.032. These are listed by model & configuration in the Luscombe Drawing list(s) that defined the, “then” current production. These drawing lists may also depict obsolete production part numbers and various configurations that were approved by the CAA & FAA at different times for use in the design. The BEST LISTING of firewall configurations is the Luscombe master drawing list that identifies all of the FAA approved configurations as they were built at different times. In consulting these Luscombe Master drawing list files, we found at least SEVEN different firewall configurations were utilized in the Luscombe 8 series airplanes. Five of these firewall/bulkhead part numbers pre-date those firewalls depicted in the 1959 Illustrated Parts Catalog, and one of those appears to be the firewall configuration installed in the subject airplane, (Part number 48124, or PN 581020). Let us now look at these different firewall configurations- ALL of which have been installed in various Luscombe models. Luscombe Master drawing list 1938-1945. Includes Luscombe Models 8, 8A, 8B, 8C, 8D., PN 48044 Firewall *1 first firewall configuration Stainless or Mild steel. PN 48124, Firewall assembly *2 second firewall configuration Budd Stainless steel (spot welded) Shown in Early Service manual / Parts guide- This unit may be equipped with a trapezoidal cut-out PN581021 about 2/3 from the bottom that allows space for the starter and rear mounted magnetos on a Continental -9 or a -12 engine accessory case where the starter is extended to the rear. The Luscombe EndowmentPage 6a, PN 581020, Firewall for starter *3 third firewall configuration A mild steel/Stainless steel stamped firewall developed for aircraft with starters. This unit is equipped with a trapezoidal cut-out about 2/3 from the bottom that allows space for the starter and rear mounted magnetos on a Continental -9 or a -12 engine accessory case where the starter is extended to the rear. 5 The Luscombe Endowment PN481021, Cover- Magneto A trapezoidal steel recess that is installed into the magneto cutout for space to install the starter and rear mounted magnetos on a Continental - 9 or a -12 engine accessory case where the starters are extended to the rear. Page 6b, PN 581055, Firewall, Lycoming *4 fourth firewall configuration Firewall designated for the 8B with a Lycoming 65- Uses different piercings, but otherwise similar to the PN581020 Page 6b, PN 281049, cover plate, firewall Removable magneto access plate for use with the Lycoming(65) firewall Luscombe master drawing list, 1946-60, includes later production Luscombe models 8A. Page 5, PN 581020, Firewall for starter Previously described above- Page 6, PN081113, Firewall, Fuselage *5 fifth firewall configuration The Luscombe Endowment This is a Flat firewall stamping blank from which 581020, 081158, and 081159 are made. This part can also be installed without cutting ANY recess holes or riveted lap joints- making the fuselage structure lighter. PN481116, Cover, Fuselage firewall, 65 HP. PN081159, Firewall Fuselage 65 HP, *6 sixth firewall configuration A mild steel/Stainless steel stamped firewall developed for aircraft with starters and generator systems. This unit is equipped with an irregular ‘round’ cut-out behind the engine that allows space for the starter and rear mounted magnetos on a Continental -12 engine accessory case where the starters, magnetos and generator drive areas are extended to the rear. For the 65HP installation, this recess cut-out is fitted with a FLAT cover plate. The Luscombe Endowment Luscombe master drawing list, 1946-60, includes production Luscombe models 8E. PN081113, Firewall, Fuselage Previously described above PN581158, Recess, Firewall Fuselage 85 HP, This recess is about 4” deep, and replaces the “flat” coverplate PN081160, Firewall Fuselage 85 HP, *7 seventh firewall configuration A mild steel/Stainless steel stamped firewall developed for aircraft with starters and generators. This unit is equipped with an irregular ‘round’ cut-out behind the engine that allows space for the starter and rear mounted magnetos on a Continental -12 engine accessory case where the starters, magnetos and generator drive areas are extended to the rear. For the 85HP installation, this recess cut-out is fitted with a recessed The Luscombe Endowment cover plate PN581158 using rivets on approximately a 2” spacing. 2 CONCLUSION / RESOLUTION FAA item #2: Because the airplane is apparently equipped with a factory style firewall and overlay with a cut-out recess such as is identified on the manufacturer’s master parts drawing list; and because it uses rivet spacing equal to or closer than the manufacturers original installation 1 , and because the installation conforms with the CAA/FAA approved type design data and CAR 04, it requires no further analysis regarding item #2 of the FAA letter dated April 27, 2009. We trust that the above analysis will provide some guidance and assistance in identifying your firewall configuration, or explaining its apparent differences from the parts manual(s) in use. Should you have further questions or need technical help, please remember that the Luscombe Endowment and Classic Aero LLC are available to assist you in Luscombe questions and repairs. Call us at 480-650-0883 or 480-917-0969, or write Mr.Luscombe@luscombe.org Doug Combs Cc file 1 The Luscombe Service manual, Section IV “REPAIRS” at “paragraph D”, states, “Rivets in a repair or patch should be the same size and spaced the same distance apart as in the original structure.” From an engineering standpoint, we know that if the rivet/fastener spacing is closer, or the diameter is larger than the original fastener spacing or the surrounding fastener spacing, the joint will meet or exceed the original design loads. The Luscombe Endowment