Stephen Whitaker wrote me in Jan.2008, for help on solving the mystery of DC-3 ECT-025.

This Douglas DC-3 / C-47 vanished without trace on 03Oct1980, north of Palma de Mallorca (the Mediterranean).

Stephen wrote:
"It was auctioned by the Spanish Air Force and left the Four Winds Airport (Cuatro Vientos) on October 3, 1980 and was never heard from or seen since. I am attempting to find any more available information such as history, flight plan files, persons who may have spoken with the pilot etc.
This DC-3 and a JU-52 which were flying together from Madrid to Germany in October 1980 to become part of an Air Museum. The DC-3 disappeared in flight, with my father as pilot.
I see three likely scenarios: 1. Ditched in the northern Mediterranean, 2. Crashed in the Spanish mountains, or 3. Recruited into clandestine service, possibly in Central America ala Ollie North.
Another DC-3 owned by Kurfiss also went missing 6-7 months later, in flight from Algeria to France.
I am attempting to reconstruct an assumed flight to prepare a video to memorialize my father's disappearance.
Any help would be appreciated."
He included an Acrobat Reader (.pdf) file in Spanish (English translation)

A posting on various fora remained without result.

Googling provided no photographs of ECT-025

The book Spanish & Portugese Military Aviation by John M.Andrade (Midland Counties Publications, 1977) offered the following information on the Spanish DC-3s:
"The first 24 of a grand total of 67 Dakota (EdA designation T.3) were supplied by the USA in 1954-55. By 1976 only a few were still in use with Escuadrones 744, 745 & 911, but late in the year the survivors had been withdrawn from use. They were put in temporary storage at Cuatro Vientos, awaiting prospective buyers, but if none are found they will be scrapped."
The book lists the serials of the C-47s (T.3s) and the closed designation would be T.3-25 (of which no c/n is given).

The identity of T.3-25 led to a report on the Aviation Safety Network, however this quotes a date of accident of 02oct1973. The report quotes T.3-25 as c/n 9037, but has no details nor a location of the accident. It does report the aircraft was written off as result of the accident.

Air-Britain's book Douglas DC-3, the First Seventy Years (2006) provided the following information of c/n 9037:
USAF 42-32811 delivered 05Feb43 - xx - Walker 11Jan45 - Smoky Hill 31Jan45 - Biggs 28Jun45 - RFC Bush 03Oct45 - NC57539 Hoosier Air Transport Corp., NYC, NY (19747) - Delta f/n 61 28Feb49 - Charlotte Aircraft Corporation - Aircraft Ferry Services Inc 30Sep59 - T.3-25 Spanish AF 29Oct61 - Without further use (wfu) 02Oct73 accident.

The webpage of AviationSafety Network has the bare minimum on the 1980 disappearance, except that it lists the operator as Kurfiss Aviation and the routing Madrid-Barajas - Perpignan,France.
Peter-Michael Gerhardt provided the following info on the Air-Britain Yahoo eGroup (AB-IX, members only):
"- Kurfiss Aviation no longer exists, not for decades (I would say since 1995, but am not sure).
- Casa 352-L D-CIAS, after having been bought by Kurfiss was flown from Spain to Germany as N88927 prior to Jun74, presumably in 1973."

This is where the trail seem to stop...

Notes to the above:
--Air-Britain (1984 & 2006 editions) DC-3 books state "T.3-25 lost 02/10/73"
--ASN does not provide an identity for the aircraft involved in 1980; no proof this is actually T.3-25
--Are there any reports of T.3-25 between Oct73 and Oct80 ?
--Aviation Letter no.168 confirms ASN record (but no ID as well) and says lost "during film work", meaning ?
--While T.3-25 would be c/n 9037 (ex/ USAF 42-32811), the referenced Spanish language PDF file states a
previous identity of 42-93461 for ECT-025. This would be T.3-67?
--Spanish and Portuguese Military Aviation by John M. Andrade list T.3-67 as c/n 13375, code 744-67 EC-AET / 42-93461

Peter-Michael Gerhardt also added on the Ju-52:
"After all I have identified the accompanying 'Ju 52': Kurfiss already had bought three in Spain (D-CIAS/CIAK/CIAL) in 1974 and 1975 and then Casa 352-L T2B-127 (coded 721-12) at Cuatro Vientos in 1979. He applied for a German permit to fly (issued 01.10.80 as D-CIAD) with the following stages: Cuatro Vientos - Montpellier - Strasbourg - Düsseldorf. In fact the flight ended in Sabadell near Barcelona and a new permit to fly was issued on 23.01.81 this time to Frankfurt. In the event Frankfurt airport refused a VFR approach due to massive IFR traffic, so that the aircraft had to land at Egelsbach on 18.02.81. Last flight was from Mönchengladbach to Saarbrücken on 23.08.82, from where it was trucked to the museum at Hermeskeil.
Korastinski was one of Kurfiss partners, being US citizen had no problems to get an FAA registration, when the German reg office demanded documents they did not had. Another common aircraft of both was DC-3 N65371, both names mentioned for it the DC-3 book."

Peter-Michael Gerhardt followed this up with a posting on the Ab-IX forum (08Feb.2008):
Günter Kurfiss has bought three DC-3s at Cuatro Vientos in 1979 for use in his "Air Classik"- exhibition on German airport terraces (see Bob Ogden`s book 'Aviation Museums' of 1979 for its beginnings - not yet solving our problem). They were:

c/n 14005/25450 43-18189 > KG773 > G-AKLL > EC-AEU > T3-62 > N8041A ferried as such to Germany (cancelled by FAA on 30.06.80) and since on display as "D-CORA" and "D-CADE".

c/n 10100 42-24238 > FL517 > G-AJAZ > EC-ADR > T3-61 > N8041B ferried as such to Germany and since on display as "N569R".

c/n 13375 42-93461 > KG616 > G-AJAY > EC-AET > T3-67 > N8041C nothing more heard of...

So, what happened with the latter?
Certainly it did not arrive in Germany nor did any Ju 52 or CASA 352 in 1980...

Only to provide more info: here are all other aircraft G.Kurfiss had owned:
D-CIAK/CIAL/CIAS/CIAD/EABO/EACK/EAGM/CAER/CJET/CONA/CONE/CONI/EBBD/EBBF/EBBG/EBS\
E
/ECAA/ECBH/ECDR/ECGB/ECGJ/ECTE/ECAD/ECBJ/ECGF/EDLO/ECMX/EFOX/EGAA/EGKA/EHWA/EHUD
/EIRF/EIHB/ELRJ/ELRK/ELRM/EMIM/EMNA/EMQO/EMWG/ENYA/EJZO/GENA/GKKD/IACM/ICCI/ICEG
/IDNL/IHBB/IKUR/IMRW/GBFD/ICAE/ICAE/ICUN/IDIM/IGAH/IJAN/IKAA/IKAB/IKAD/IKAF/ILIS
/ILSY/IKUC/IDKL/EDTQ.

So the last posting would mean that "T3-67 > N8041C nothing more heard of..." could be the sought after ECT-025...

More information welcomed.