Analysis by Tom Palshaw

Note:  The views and opinions in this report are solely those of the author and do not reflect those of any organization or person. The data used was publicly available from TIGHAR publications, related reports and blogs. DC-3 data is provided here so that the reader can review the data and make up their own mind. While I am supportive of TIGHAR's theory that Earhart landed on Gardner Island, I do not believe 2-2-V-1 came from a Lockheed 10.

INTRODUCTION

I became involved with artifact 2-2-V-1 back in 1992 when I mapped the rivet pattern in the belly of the New England Air Museum's Lockheed 10. Over the years the artifact has been subjected to many scientific tests and speculation as to its source. This discussion continues to this day. TIGHAR's operating theory was that if the artifact did not come from any other contemporary aircraft it must have come from Amelia's aircraft. I will present data that supports the idea that the artifact matches the right wing upper skin of a DC-3 of a certain serial number range.


ARTIFACT 2-2-V-1 / C-47B WING CHARACTERISTICS

These questions can be divided into two categories:
1. Deliberate characteristics (original design features) and
2. Consequential characteristics caused by events during the life of the artifact.

Deliberate characteristics include skin thickness, material composition, and structural attachment. They also include rivet type, size, pitch, and location. If any of these characteristics differ between the artifact and the wing then it can be said that the wing is not the source of the artifact.

Consequential characteristics are caused by events experienced by the artifact over time. It cannot be assumed that all features occurred at the same time. Artifact 2-2-V-1 shows clear evidence of a violent crash. It also shows signs of post crash cutting and repetitive fatigue bending fractures. While these features help to define the artifact, they might not eliminate the C-47B wing as its source as described here later.


DELIBERATE CHARACTERISTICS

The similarities between the artifact and the wings of a DC-3 were first noticed while restoring New England Air Museum's DC-3 (C-49J) s/n 6314, AAF# 43-1973, registration NC-55792 that was built in 1942. While much of the data matched, the skin edge near the -5 rivets was in the wrong orientation.

The museum also owns a spare wing in storage from a C-47B-DK, s/n 15013, AAF# 43-49197, registration N74844. This aircraft crashed at Bradley Field, CT on July 16, 1971; see Appendix I. A paper template of artifact 2-2-v-1, minus the tab, was made utilizing dimensions published in TIGHAR TRACKS , April 30, 1992, vol 8 #3. See photo below.

The 2-2-V-1 Template Laid Over the NEAM C-47B Wing.  Source: Tom Palshaw

MATCHING CHARACTERISTICS

TIGHAR visited the New England Air Museum on July 16, 2017 with artifact 2-2-v-1 to inspect the wing in storage. The inspection was video taped but TIGHAR has not released that tape to the public. Several questions were raised during the inspection that required further inspection. That additional inspection was conducted on July 18, 2017. The results were emailed to TIGHAR. See Appendix II for information about measurement methods.

Rivet size: The size of the rivets in the area of interest on the C-47B wing was questioned. During the follow-up investigation one rivet was removed from the wing in this area on Tuesday, 7-18-17. This confirmed the rivets in question were -3 brazier head rivets. These match the known rivet size and length of the artifact. (Side note: The rivets on the C-49J wing, constructed 1942, are also -3 rivets.) The thickness of the underlying stringer was measured and found to be 0.060" thick.


Rivet pitch variation of the -5 rivets: Artifact 2-2-V-1 has rivet pitch variations of the -5 rivets. It was initially assumed that C-47B wing rear spar** rivets had a constant pitch of 1.25”. When re-examined on 7-18-17, it was found that the wing rivet pitch varied randomly from 1 3/16 to 1 9/16 inches; see photo below.  There was no obvious reason for these variations. This new information should be compared with the data from the Artifact 2-2-V-1.

Irregular Spacing of -5 Rivets on C-47B Wing.  Source: Tom Palshaw

WHAT ON ARTIFACT 2-2-V-1 MATCHES THE WING OF A C-47B?

  • The artifact and the wing skin are 0.032" thick Alclad aluminum.
  • The -3 brazier head rivets have 1" pitch and 0.060" underlying stringers.
  • The stringer alignment matches the data published in TIGHAR TRACKS.
  • The -5 brazier head rivets match the varying pitch of the tab and the rear spar** of the wing. The spacing between the rows of the -5 rivets matches the rear spar** of the wing.
  • The artifact rows of -5 rivets do not match the lower frame of the Lockheed 10 window. The Lockheed 10 rivets were smaller and more closely spaced; see photo below.  This indicates that the artifact did not come from Amelia's airplane.

Lockheed 10 Window Frame.  Source: TIGHAR

  • The s/n of the Sydney Island crash (13890, 1943 ) and the Bradley crash (15013, 1944 ) are reasonably close.
  • The only surviving component from the crash on Sydney Island was the right wing, which broke off when it hit a tree, C-47A, s/n 13890, AAF# 43-30739.
  • The Gilbertese settlers were known to travel to Sydney Island and salvage material from crashed aircraft.
  • The chemical composition of the artifact matches World War Two aluminum, not 1930's aluminum; see table below. 

 Lehigh Testing Lab Chemical Analysis Data, Job # R-48-20 Dated Jan 6, 2015. Source: TIGHAR

CONSEQUENTIAL CHARACTERISTICS

It was assumed that the fatigue failure on artifact 2-2-V-1 was caused by back and forth bending of the artifact while still attached to the source aircraft. This cannot be proven. The bending could have occurred later.  The fatigue failure lines are so straight as to have another possible meaning. If the artifact had been wrenched from an attached underlying structure the fracture line should have been more uneven based upon the variance of stress at and between attaching fasteners.  It is quite possible that artifact 2-2-V-1 was originally larger when removed from the source aircraft. A piece could then have been removed later by placing the artifact between two straight angles and flexed to failure by locals to make handicrafts. This would better explain why the fatigue fracture is absolutely straight.

** - Note: As originally published, this report mistakenly referred to the center spar of the NEAM C-47B wing as the location of a line of -5 rivets that corresponds to a line of -5 rivets on 2-2-V-1. The rear spar is the correct location of that rivet line, as the report now states.

CONTACT

Questions and comments can be sent to the author at:

See the Ghost of Gardner Island blog for additional information determined after this report was written.

REFERENCES
TIGHAR TRACKS, April 30, 1992, vol 8 #3, page 5.
NTSB Report # 92-40, Mar 5,1992, DCA 37-I-A001, July 5, 1937
‘The Crash at Sydney Island’ TIGHAR Project Report #7, 7/26/98
Lehigh Testing Lab, Job # R-48-20 Dated Jan 6, 2015
Air Safety Network accident reports (Flight Safety Foundation)


APPENDIX I:  C-47 ACCIDENT REPORT

APPENDIX II: MEASUREMENT METHODS

Let me start by making a blanket statement: All rivets are identified by the size of the shank, not by the size of the head.

To identify installed rivets in any structure would require determining both the shank diameter and the grip length. Rivet diameter is in 1/32", grip length is in 1/16". A -4 rivet is 4/32" in diameter. Reference FAA Mechanics General Handbook AC-65-9(1970), Chapter 6, page 127, figure 6-31 shown below.



The rivet may have to be removed to accurately determine its true characteristics. This should be done to a standard practice such as FAA Airframe Manual AC65-15, Chapter 5, page 167 to ensure that the rivet hole is not enlarged or damaged.

Brazier head rivets are obsolete so technical data is harder to find. The Aircraft Mechanics Handbook published by Chas. A. Bennett Inc. in 1944 contains a chart for Brazier head rivets. See chart below from Section 2, page 5, figure 6 of that manual.


This chart shows the standard head dimensions of a brazier head rivet. Brazier head rivets were available under two standards, AN455 and AN456. When the supply of these rivets were checked at the New England Air Museum collection it was found that brazier head rivets can have two head sizes of the same dash number. See the photo belowof these samples.


It would be nearly impossible to accurately determine the rivet size by just looking at the head. The rivet must be removed from the structure. This is the process that was performed on the C-47B wing; see  photo below.



Once the rivet is removed, check the hole size by inserting the appropriate drill. Reference Canadair Challenger Structural Repair Manual (1981), 51-42-11, page 6, figure 4, shown below.


The same procedure was performed for the -5 rivets. Note also the variations in the rivet pitch of the -5 rivets.

To determine the grip length it was necessary to first measure the skin thickness. This was done by using a micrometer at the edge of the skin. To measure the grip length a "calibrated" cleco was used to compare a known stack up of aluminum to that of the wing. The result was a skin thickness of 0.032" and a stringer thickness of 0.060". This is similar to the NTSB Report.

One final note; When the wing of the DC-3 (C-49J) built in 1942 was compared to the same area on the C-47B wing built in 1944, the structure was completely different. It is important that when researching this issue, the c/n of the aircraft should be close.