Gillam Survey

Research Results
Some of the aluminum composite structures recovered from 49-KET-00910 are dados, but they do not resemble the dado-like objects recovered from Nikumaroro. This lack of similarity between dados from the Gillam site and the purported dados from Nikumaroro has resulted in a new hypothesis about these components.

The auxiliary fuel tank documented in the wreckage of NC14915 was most likely a necessary modification prompted by unusually long distances flown in service to Morrison-Knudsen. The tank was installed in the left side of the cabin just aft of the main beam, which required the removal of two passenger seats. Heater ducts pass along either side of the cabin floor where it meets the cabin walls. Thus, the left heater duct passed closely beside the auxiliary fuel tank. In order to prevent the heat from the duct reaching the fuel tank, a layer of heavy asbestos matting was installed over the ductwork and held in place by a dado attached to the cabin wall and through the asbestos to the heater duct.27

Auxiliary fuel tank pulled aside revealing wooden mounting slats and asbestos matting installed over the heater duct and held in place by a dado.

The Gillam wreckage has provided documentation of an insulating barrier between the heater duct and a fuel tank installed in an Electra cabin. This has led to the formulation of a new hypothesis regarding the function of the structures found on Nikumaroro that TIGHAR thought may have been dados. We have tested the hypothesis that the objects found on Nikumaroro were dados from a Lockheed Electra and found the results to be negative. We now suggest that these objects are, in fact, shields used as an insulating barrier to protect the auxiliary fuel tanks from the ductwork carrying hot air through the cabin.28 (Appendices 3 and 4)

TIGHAR had originally postulated that the dado-like objects from Nikumaroro had been installed along the juncture of the cabin wall and floor. However, as the Gillam wreckage exemplifies, passenger cabins of Lockheed Electras were heated with hot air vented into aluminum ducts located where the walls meet the floor. In order for the dado-like objects to function as actual dados (protecting control cables) they would have to be mounted behind the heater ducts. Existing photos show standard heating ducts were installed in Earhart’s Electra.29

This photo clearly shows the heater ducts installed in the cabin of NR16020. Although it cannot be determined from this image whether the ducts extend forward beside the fuel tanks, hot air entered the ducts forward of the location of the tank in NR14915.

There are rust marks at holes located along the top edge of the most intact dado-like object from Nikumaroro that indicate the former presence of a rectangular hardware attachment fixture similar to a timmerman nut (Appendix 3). Initially, it was thought that these holes allowed for hardware to attach the structure to some part of the aircraft such as the interior cabin wall. It appears now, after comparing the Nikumaroro structures with the known dados from the Gillam site, that what were presumed to be mounting holes are openings for fasteners to secure insulation to the heat shields (formerly presumed to be dados). There were also remnants of quarter inch thick insulating fabric that resembled cork covered in a blue, woven fabric on this most complete putative heat shield from Nikumaroro.30

The absence of mounting holes on the top edge of these structures indicates that they were attached only by means of screws or nails through the 90-degree flange found on the bottom of the structures. The presence of what appear to be pry marks on the bottom of the flange on the Nikumaroro structures suggests nails were used. The floor of Lockheed Electras, as the Gillam wreck confirms, was comprised of plywood covered with linoleum nailed into place.31

Thus, we hypothesize now that the Nikumaroro objects formerly known as dados are heat shields. They appear to have been freestanding cantilevered structures nailed to the floor standing end to end along the heater ducts. There are no extant photographs of the cabin of the Earhart Electra immediately prior to the installation of the auxiliary fuel tanks. The interior photos that do exist (see above) do not illuminate the narrow space between the tanks and the cabin wall.32

This conceptual image of the purported heat shields installed in the Earhart Electra shows one installed between the heater duct and the location of the auxiliary fuel tanks with the insulated side facing the ductwork.

It is possible that asbestos matting was used on NR16020 just as it was used on NC14915. However, the quantity of asbestos that would have been required in the Earhart Electra would carry a substantial weight penalty for a record world flight attempt. The putative heat shields found on Nikumaroro are, by comparison, very lightweight. The examination of the Gillam wreckage provided solid evidence to support the inclusion of some form of insulating shield adjacent to the heater ductwork within the Earhart Electra. Further research is necessary.33

For the first time TIGHAR closely examined a Lockheed Electra crash site that shows a remarkably small incidence of disturbance, and remains almost complete. Throughout the wreckage, the team observed the same blue protective paint coating on interior aluminum surfaces found at the Livermore/Haid crash site on the St. Joe National Forest (NC14935). Quite distinctive and believed to be a protective paint coating applied to metal components prior to the assembly of the aircraft to resist corrosion, this material may be useful for comparison with some enigmatic remnants of surface coating detected on a large section of aluminum aircraft skin found on Nikumaroro.34 A number of the artifacts recovered from the Gillam aircraft wreckage exhibit this blue coating. The glass fragments and floor covering material recovered may also be useful for comparison to like objects recovered from Nikumaroro. Additionally, the existence of an auxiliary fuel tank, a feature consistent with the Earhart Electra, may allow for further comparison as research progresses.

27 “The Ketchikan Wreck,” TIGHAR TRACKS 20, no. 3 (December 2004): 8.
28 Ibid.
29 “The Un-Dados,” TIGHAR TRACKS 20, no. 3 (December 2004): 31.
30 Ibid, 33.
31 Ibid, 31-33.
32 Ibid, 31, 33.
33 Ibid, 34.
34 “Section C. Construction,” Specifications, Equipment and Maintenance for Model 10-A, 10-B and 10-E. (Burbank, CA: Lockheed Aircraft Corporation, Revised January 26, 1937).

Introduction Purpose Background Research Fieldwork Site Description Aircraft Parts Recovered Interpretation Research Results
Eligibility for National Register Acknowledgements Bibliography Appendix 1: Site Map Appendix 2: Lockheed Electra Appendix 3: Putative Heat Shield Appendix 4: Putative Heat Shield/Lockheed 10B Appendix 5: NC-14915 & WSC-146

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