Part 5 – Analysis of the Primary Evidence

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COPYRIGHT 2004 – 2020
The contents of this website are Copyright to David Billings. No portion of this website story may be used without permission. All Rights to the content of this story based on the Earhart Lockheed Electra 10E aircraft being on New Britain Island are Copyright to David Billings and the story is the Intellectual Property of David Billings.


The primary available evidence is, of course, found on the bottom of the “D” Company, 11th Battalion, 13th Brigade wartime map. The map is authentic, and the handwriting appears to have been written in 1945. The longtime map holder, Len Willoughby, who retrieved the map from a map case from a pile of discarded equipment in 1945, kept the map until he mailed it to Don Angwin in 1993. Neither of these gentlemen had the motive nor “insider” expertise to create or introduce details concerning the Electra’s obscure component identification or situational nuances. The string of numbers and letters, “600H/P. S3H/1 C/N1055,” remains the most significant historical notation found to date in the search for Earhart’s aircraft. We believe this alpha-numeric sequence references the details on the metal tag recovered from the engine mount by Warrant Officer Nurse on 17 April 1945. This three-group sequence translates to 600 Horsepower, Pratt & Whitney R-1340-S3H1, Construction Number 1055. Of these three groups, two are engine parameters and one is an airframe identifier. Construction Number 1055 is the airframe identifier and decodes to Model 10, 55th built. This airframe construction number IS Amelia Earhart’s Lockheed 10E Electra aircraft. The eyewitness visual description from two of the Australian veterans present at the crash site strongly support this determination. Lets look closely at the notation.



Why is an Airframe Identifier Attached to an Engine Structure?

The question of why an airframe construction number on a metal tag was wired to an engine mount was puzzling until I called to mind that the aircraft, Amelia Earhart’s Lockheed 10E, suffered landing gear, wing, tail, engine mount and engine damage from her ground loop while attempting take-off from Hawaii. Then, Amelia was on her first attempt at flying around the world, west-about. She ground-looped the Electra and it was severely damaged. It was disassembled, packed up and sent back to the Lockheed Burbank factory.

Ground loops, where the landing gear collapses and/or the propellers strike the ground at power, bow, bend or break engine mount tubing trusses in addition to all the other damage that can occur.

Immediately after the ground loop in March 1937, the aircraft is shown resting on the ground with the right hand No.2 engine pointing skywards. There is a large pool of oil under the No.2 engine, indicating that the right side engine mount must have collapsed completely, the engine bulk piercing or crushing the oil tank, which is nestled within the mount, forward of the firewall. The left hand No. 1 Engine is shown to be only slightly out-of-line, and the corresponding engine mount had been pushed backwards buckling the firewall. Also, the left hand gear and wheel had buckled the outboard side of the nacelle in the area of where the engine mount tubing lower truss beam would be, meaning that the lower tubing was probably bent. [20Mar1937_Electra_Accident_Report_Maxwell]


During the repair process, the Electra was given a new engine mount for the No.2 engine. As Lockheed did not supply a new mount for the No. 1 engine, then this says that the No.1 engine mount was repairable. To repair the mount, it would be secured in a manufacturing jig at the bolt mounting points after the damaged sections had been cut out. New sections would be welded in by the oxy-acetylene gas welding method. Former President of the Amelia Earhart Society, Mr. Bill Prymak, furnished information that the engine mounts were made at an unnamed foundry in Los Angeles. It would be a normal practice for that originating foundry to be the place where the mount could be repaired as they would have the original production jig. Items sent for a gas flame welding shop repair would get fireproof metal tags not card tags, just as they would do today.

To identify the left hand engine mount as it was dispatched for repair, it would be necessary to identify the item to track it with any written Purchase Order detailing the repair required. I very much doubt that in 1937, an aircraft metal working foundry in Los Angeles would be inundated with engine mounts in for repair so basic identification would be all that was required on the item. The associated paperwork would have the detail.

Why is an Airframe Identifier Attached to an Engine Structure?

Lockheed were building a few variants of the basic Electra Model 10 in 1937. These variants had similar engines of differing horsepower – some 450 horsepower, some 550 horsepower and some 600 horsepower – so one requirement would be to identify the horsepower to be supported by the mount. What is the horsepower rating of the mount? “600 H/P.” The associated engine type also has differing mounting holes. Which one is it? “S3H1.” Which aircraft is it from? “C/N 1055“. What do we use to tag it? Not a paper card tied on with string since we are sending this engine mount to a welding shop where an oxy-acetylene flame torch is going to be used. So we will use a metal tag attached by wire. Hence, we etch or stamp “600H/P. S3H/1 C/N1055” on the metal tag made from a scrap piece of aluminum or tinplate and drill a hole in it and finally wire it to the damaged engine mount.

In 1937, the Electra was repaired mostly where it had been made and workers in the Lockheed factory would identify all components removed during the repair for in-house and out-sourced work with its construction number,“C/N1055“, and not from its civil aviation registration, “NRl6020.” This is standard procedure at an aircraft manufacturing company where aircraft are known by their Build Serial Number, not by their registration letters or numbers as the case may be. I have worked at aircraft manufacturing and have visited another manufacturers, and the aircraft assembly bays are always identified by the “manufacturer’s number.” In this case, Lockheed used the term “Construction Number” abbreviated to “C/N.” In modern times, we now use the term “Manufacturers Serial Number” abbreviated to “MSN”.

Putting It Together

I have been in aircraft engineering for 59 years, and as a professional I consider the small metal tag, wired to the mount tubing of the detached engine, and removed by Warrant Officer Nurse, was actually the metal Repair Tag which had been left on the engine mount truss after repair and re-installation. In aircraft engineering hangar procedures it is not normal in everyday paperwork to see airframe and engine component designators or related equipment-identifying codes come together in one place on a component. One such place where they do intersect is on a Repair Tag. An engine mount by its nature is classed as an engine component and so any airframe identifier listed on a repair tag would be there to show which aircraft the component came from (and belonged to), in this case “C/N1055.” It is quite normal for any component removed from an aircraft to have a Repair Tag.

Today, it is standard operating procedure to remove Repair Tags when refitting components back on an aircraft, and these tags or cards are sent with all the other “Check” and/or “Defect Repair” paperwork to the Aircraft Records Section for inclusion into the individual aircraft file. Yet still, very occasionally, these repair tags are left on components after the completion of work and a “find” order is issued by Records Section or Quality Assurance to retrieve the tag and to send it to the Aircraft Records Section. In my experience over the last ten years, I have known this happen about five times.

As previously confirmed, the Pratt & Whitney “Wasp” S3H1 variant is correct for Earhart’s Electra.   Initially when I commenced on this research, all evidence pointed to a pre-WWII horsepower rating for the R-1340 S3H1 as 550 horsepower. I could not understand why the writing on the map had “600 H/P.” next to the engine type code “S3H/1.” As I discovered, the explanation is simple: 600 H.P. is available with the S3H1 when using 100 Octane gasoline. The higher octane number (100 as against the normal 87) is a higher “anti-knock” or “pre-detonation” value. The full power obtainable with the 100 Octane fuel is in fact 600 horsepower. Lockheed Report 487: “Long Range Study of a Bi-Motor Airplane” concerned with the Lockheed Model 10E does state that the engines are indeed rated at 600 Horsepower.


Do not confuse the possibility that the patrol found an engine serial number with the repair tag (translated to the map) data. An engine serial number was neither seen or found nor was it expressed on any documentation from the Patrol A1 activities. The discreet details and sequence of engine type, horsepower and airframe number are extremely difficult to concoct. There is no possible way that an Australian infantryman would have known Earhart’s Electra 10E airframe construction number or horsepower rating or engine designation in 1945. We also have examined the possibility that C/N may have been confused as S/N, as a serial number for the engine; no such engine serial numbers exist for Pratt & Whitney engines then and now. We could only “wish” that the patrol did find an engine serial number…

 The Date on the Map

At about the time of the date on the map edge “[24/5/45],” 24 May 1945, the Australians were informed that “…the Americans say that it is not one of theirs…” or words to that effect. Therefore, a branch of the United States Army or Army Air Force had been informed of the engine (or aircraft) wreckage found during the patrol a month earlier.

Some five weeks after the Patrol A1 was completed, “D” Company personnel were at a beach near 13th Brigade and 11th Battalion Headquarters near to Tol Plantation, waiting for a barge to transport them further up the coast to the Unamitki River. They were approached by an unidentified officer from headquarters, who informed them that the U.S. Army had replied to the report of the find of the engine (or aircraft). The officer was reading from a signal (message), and told the assembled men that the US Army (which included the USAAF) had said that it was not one of their engines, therefore not their aircraft. The officer mentioned it was a Wasp engine and was most probably from a civilian aircraft. Some of the veterans reportedly heard that the aircraft could be a Lockheed as they were big users of Pratt & Whitney engines. They were told not to worry about it, as they had other things to do.

Lieutenant Backhouse believed the metal tag was sent to the Americans as supporting evidence along with textual documentation, possibly a copy of the missing patrol report annex (Report 63A). The hope was that the Americans could account for a wartime loss that the patrol had stumbled upon. Ken assumed that the tag was sent from New Britain to Port Moresby by military-channeled surface mail in a courier bag. Actually, the nearest Americans were at Jacquinot Bay about 80 miles away and their LCM’s had regularly visited Wide Bay on a schedule of re-supply runs to Tol Plantation troops and to Kalai Plantation troops. These Americans of Company “B” of the 594th EB & SR had a very close working relationship with the Australian Army.

In any case, whichever American unit received the metal tag or the information concerning the metal tag, any official response back, if any, to the Australian unit normally would take some time. Of course, it was about five weeks when the men of “D” Company heard an official reply.

The Question of the American Visitors

Before the negative message response concerning the tag arrived back at “D” Company, there had been some immediate curiosity from the U.S. Army or Army Air Force as two American officers visited the “D” Company area at Kalai Plantation. Upon arrival they requested to speak to Lieutenant Backhouse. The visit was late April. Lieutenant Backhouse was not available as he was out on another patrol when they arrived. Strangely, these two US Army officers could not wait and left.

Between the time after the Patrol A1 Report was submitted on 19th April and the time of the writing on the map, 24th May, all of Backhouse’s patrol listings indicate one-day duration jungle patrols. However, there is one patrol – not logged – that we established he was a member of. A patrol to the Melkong River was scheduled as a two-day patrol. As alluded to, there likely would be only two source locations from where U.S. Army officers would come from to meet with Lieutenant Backhouse at the Kalai Plantation:

1) From a U.S. Army unit left in New Guinea as a liaison with the Australians in New Guinea.

2) From the U.S. Army 594th Engineer Boat and Shore Regiment (EB&SR) at Jacquinot Bay.

In the first case, the most logical source would be Port Moresby as the 1st Australian Army had a liaison group there. This is some 500 miles from Wide Bay. The officers would need to be prepared for a stay at Kalai Plantation after traveling nearly 500 miles. It would not be a one-day task. This action would in all probability entail a flight by aircraft from Port Moresby to Jacquinot Bay which had an airstrip, and then a sea trip by barge or boat.

In the second possibility, the two officers may have come up from Jacquinot Bay on a regular re-supply run and take the next scheduled returning barge back to their unit. However the 594th “unofficial history” in my possession carries the statement that their barges (LCM’s) left Wide Bay on the 15th April for the “last” time as the Australian 41st Landing Craft Unit (LCU) took over from the American 594th. Of note, the 594th had three “fast” sea craft called J-Boats and there was also mention of a “Picket Boat” which was capable of over 20 knots speed.

No matter their origin, why could these two officers not wait? Anyone from Port Moresby equipped for a trip of a few days certainly would have waited until Lieutenant Backhouse returned from any of his short patrols. On the other hand, why would two “locally-based” officers (of the 594th) not announce that they would be back at a later date, and come back on one of the boats that they had? I needed to isolate the day in question.

Warrant Officer Keith Nurse remarked that Lieutenant Backhouse was in a bit of trouble with the chief topographer when he got back from Patrol A1, because he could not definitively state where the patrol had been except for a location on the Mumus River. As was revealed in archived message traffic, Captain Mott, the Topographic Survey Officer, had an extraordinary interest in the area and the observations of this unit’s first patrol in the jungle. Captain Mott reportedly became somewhat agitated and it resulted in a heated disagreement between Captain Mott and Captain Geikie, the “D” Company Commander.

As a result of this altercation, Backhouse was sent out on another patrol almost immediately. From the Patrol Report Ledger, and a letter report in the Australian War Memorial archives, we can get a good picture of what patrols Lieutenant Backhouse participated in from April 19th to May 24th.

Possible opportunities for the American officers to meet with Backhouse:Part05-Sketch02

We can see from this table that the most likely day for the visit to Kalai by the U.S. Army officers was 21 April – Backhouse was still on patrol.

As to the question of why the two officers could not stay and departed quickly is twofold. Officers traveling from Port Moresby would expect to stay a couple of days due to transportation scheduling and having a justifiable mission. Therefore the officers did not come from Port Moresby; instead they came from Jacquinot Bay – the 594th EB&SR. There also is a simple answer as to why they could not wait. Their unit, Company “B” of the 594th EB&SR, was under orders to depart Jacquinot Bay at 0330Hrs on 22nd April, bound for Finschaven and then Hollandia to rejoin their regiment there. We know with certainty that Lieutenant Backhouse was on patrol on the 20th and 21st, probably returning by 1800 hours on the 21st. Backhouse was definitely at Kalai on the 23rd as he wrote a letter report to his Company Commander, therefore the 594th officers could not have arrived on that day because they had already shipped out from Palmalmal at Jacquinot Bay, so the only “day of opportunity” for the officers to get up to Kalai was 21 April. How did they get up to Kalai so quickly as the barge trip is 10 hours at best and ten hours back? The answer is that the 594th owned three J-Boats – small fast boats – and there is also the mention of a “Picket Boat” capable of over 20 knots in speed (23 mph). Also, on the night of the 21st April at the 594th base at Jacquinot, a “Farewell Party” had been organized for the departing Americans. The 594th sailed away from Jacquinot Bay at 3:45 am, April 22. In view of the 594th Unit Movement Orders and the sea-transit time of what must have been 4 hours to get back to Jacquinot Bay after 4 hours to Kalai, and on hearing that Backhouse was not available, the two officers would be keen to get back in daylight; if not for the party arranged for their unit by their Australian hosts.

The conclusion is that the American visitors were from the 594th EB&SR, as no other American personnel visited Backhouse after that missed opportunity either at Kalai or at Tol Plantation.

What we seem to have with this episode is direct interest from one unit of the U.S. Army (594th EB&SR) that included a convenient visit to try and gain official or passing information for themselves or another requesting unit; and no interest, based on the tag information, in the form of a message response from another component of the U.S. Army some 5 weeks later. The research continues as to what surviving members of the 594th heard or saw about an aircraft wreck in April 1945.

Potential Sources of Aircraft Components in the Wide Bay Area

Civilian Aircraft

There were two Lockheed Model 10A aircraft in New Guinea operated by Guinea Airways based at Lae. These aircraft had Pratt & Whitney R-985 engines of 450 horsepower and both of these were evacuated to Australia at the outbreak of war in 1942. They did not return to New Guinea with any permanency during the war except that one aircraft did accomplish supply runs to the Poppondetta area during the battles for Buna-Gona-Sanananda, and other places in New Guinea away from the fighting zones. It returned safely to Australia. There were no known Japanese civilian aircraft with the same engine type in New Britain.

Military Aircraft

I have been unable to find any evidence that any R-1340 S3H1 direct drive powered aircraft other than Earhart’s Electra flew in New Guinea prior to or during World War II. There were some Australian Wirraway aircraft powered by licence-built Pratt & Whitney R-1340 S3H1-G engines. There were seven at Rabaul when the Japanese invaded on 23 January 1942. Of these, five were shot down over Rabaul, and two escaped to Port Moresby. One flew on to Australia and one remained in Moresby. These “G” engines were a geared variety (they had a reduction gear at the front of the engine) and drove a three bladed propeller developing 650 horsepower. Furthermore, the patrol identified a twin-engined aircraft, the Wirraway was a single-engined aircraft. Other Wirraways operated in New Guinea but were not sent against Rabaul.


Furthermore, an enquiry to the USAF Museum at Wright-Patterson AFB, brought an interesting response from a curator, David Menard. I have had several communications with David over the years. David looked through all the available listings of USAAC, USAAF, USAF, US Army, USN, USMC, and USCG, up until and including 1937, for any use of the R-1340 S3H1 engine, and all he found was some early biplane types and prototypes undergoing evaluation by the military. They had the “civilian” S3H1 engines, but when accepted into military service, those aircraft were then listed as having the AN-1 military version and designation of the Wasp engine. Each arm of the U.S. military used their own designations. David looked into the use of the AN-1 engine employed on any aircraft sent to New Guinea during the WWII conflict and could not find any use of that engine in New Guinea by any arm of the U.S. military.

When the Australian patrol’s mysterious nacelled engine and airframe were found, the Japanese had been on New Britain for 3 years and 3 months. Aerial activity against Rabaul started in 1942 with sporadic raids by four-engined Flying Fortress B-17’s operating from Australia and re-fueling at Port Moresby. Major aerial hostility did not start until late 1942 when the U.S. 5th Air Force achieved a worthy strength, and airbases were opened up on New Guinea Territory. The jungle wreckage find in 1945 was a bare aluminum nacelle and a bare aluminum airframe according to the veterans who actually saw the wreckage. In contrast, wartime allied aircraft were camouflage painted. I have been to USAAF wrecksites (B-24’s and a B-17) in Papua New Guinea and have seen wrecks of Japanese aircraft at their resting places at Madang and Kokopo. The museums in Port Moresby and Kokopo have aircraft out in the open. None exhibit the amount of corrosion described by Keith Nurse, “holed and filigreed.” It would be almost impossible for a wartime aircraft on New Britain to have corroded so badly after a maximum of three years. For Amelia’s Electra, it would have been there eight years. The bare aluminum cowling must have had a layer of impinged salt upon it to have been degraded so badly. Earhart was low over the sea after take-off from Lae until out of sight and she purportedly was also at 1000 feet whilst looking for Howland Island. Even today, wartime aircraft cowlings out in the open at Kokopo, near Rabaul close to the sea, do not exhibit that kind of corrosion.

Examining WWII Aircraft Wreckage at the Kokopo Military Museum


Part 1 – The Beginning | Part 2 – PNG History/Topography | Part 3 – Wreckage is Found
Part 4 – Tangible Evidence | Part 5 – Analysis | Part 6 -Lae to Howland Island
Part 7 – Howland area to New Britain – To the Gilberts…
Part 8 – Howland area to New Britain – Flying Westwards for Rabaul
Part 9 – Not Seen, But Not Forgotten
Part 10 – 2017 Expedition Overview
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COPYRIGHT 2004 – 2020

The contents of this website are Copyright to David Billings. No portion of this website story may be used without permission. All Rights to the content of this story based on the Earhart Lockheed Electra 10E aircraft being on New Britain Island are Copyright to David Billings and the story is the Intellectual Property of David Billings.