There were a few B-17s that were converted for use as commercial transports during the immediate postwar years. The B-17 was not well-suited as a commercial transport, and none of these transport conversions were very successful.
Following the end of the war, a surplus B-17G-105-VE serial number 44-85728 was purchased by Trans World Airlines for conversion as an executive transport. Following TWA's purchase of the surplus B-17G, it was ferried to Boeing's Seattle plant for the conversion work. All of the military equipment was removed and the fuselage was fitted with additional seating, and additional windows were cut into the sides of the fuselage. Since Boeing had by now used up all the letters of the alphabet for sub-variants of the Model 299 series, the company had to start through the alphabet all over again in designating later versions, and the conversion was assigned the company designation of Model 299AB.
The first civil registration assigned to the Model 299AB was NX-4600, but this was soon changed to NL-1B, the L being a new symbol introduced in the immediate postwar years to designate former military aircraft that had been converted to commercial uses. These sorts of conversions were given a limited type certificate of LTC-1, since they could not qualify for the standard licenses that purely commercial types were given. One restriction of the LTC-1 type certificate was that these conversions were not allowed to fly paying passengers.
TWA used the Model 299AB for survey and liaison work in setting up its routes in the Middle East. So far as I am aware, it never flew paying passengers. At the end of 1947, the machine was given to the Shah of Iran, and the Iranian registration was EP-HIM, where the HIM stood for "His Imperial Majesty". The Shah's B-17 was scrapped for spares at Creil, France in 1970.
Bolivia used a total of 26 B-17s in their civil aviation fleet by several different operators. Most of them were acquired from the civilian market, but eight B-17s were transferred to Bolivia directly from USAF surplus stocks in 1956. These planes were assigned Bolivian civil registrations between CP-620 and CP-627. Hamilton Aircraft of Tucson was contracted to prepare the aircraft for delivery to the Bolivian government. An additional seven B-17 airframes were supplied to Hamilton Aircraft for scavenging for spare parts to keep the remainder flying.
Here is a list of Bolivian B-17 transports.
USAF serial Bolivian serial Disposition 41-9210 CP-753 ex N9720F. Returned to US as N8WJ for restoration. 41-24434 CB-79-->CP-579 ex N60475. Destroyed Dec 1958. 42-3360 CB-70-->CP-570 ex N67974. Destroyed Sept 1955. 42-3470 CP-633 ex Nicaraguan AN-AMI. Sold to Colombia as HK-580. Ultimate fate unknown. 42-6073 CP-686 ex-N7942A. Destroyed Nov 1968. 42-30921 CB-71-->CP-571 Destroyed Jan 1962. 43-37650 CB-97-->CP-597 ex-N66570 - Destroyed Sept 1955. 43-38322 CB-80-->CP-580-->CP936 Destroyed Feb 1972. 43-39307 CP-625 Transferred to Bolivia from USAF in 1956. Destroyed Nov 1957. 44-6332 CB-88-->CP-588 Destroyed May 1963. 44-6393 CP-627-->CP-891 Returned to USA in 1981 for display 44-6556 CP-624 Transferred to Bolivia from USAF in 1956. Destroyed Feb 1963. 44-83750 CP-623 Transferred to Bolivia from USAF in 1956. Destroyed 1958. 44-83809 CP-626 Transferred to Bolivia from USAF in 1956. Destroyed 1959. 44-83858 CP-742 ex-N5226V. Destroyed Feb 1965. 44-83859 CP-767 ex-Peruvian OB-R-623. Destroyed April 1967. 44-83861 CP-741 ex-N5227V. Destroyed Oct 1965. 44-83875 CP-640 ex-N5231V. Destroyed August 1967. 44-85774 CP-621 Transferred to Bolivia from USAF in 1956. Returned to USA in 1968. Destroyed 1973. 44-85806 CP-762 ex-N117W. Scrapped Dec 1964. 44-85817 CP-622 Transferred to Bolivia from USAF in 1956. Destroyed Feb 1957. 44-85824 CP-694 Ex-N9347R. Destroyed Dec 1963. 44-85840 CP-620 Transferred to Bolivia from USAF in 1956. Returned to USA in 1968 as N620L. Destroyed July 1973.
There was one place where the B-17 did fly paying passengers--Sweden. During the war, sixty-eight B-17s flying over Germany had been forced to divert to Sweden when their crews found that they were unable to return to England. Since Sweden was neutral, these planes had to be interned and their crews sent to camps. A program was worked out in late 1944, in which the crews and other interned Americans were allowed to return to England. In exchange, the US government agreed to let Sweden "purchase" nine of the interned Fortresses for $1.00.
Swedish authorities converted seven of these planes into commercial transports for the SAAB airline, stripping them of their military equipment and installing airline-type seating. The nose windows were removed and the length of the nose was increased in order to make room for more passengers. These B-17 airliners were operated for several postwar years before being replaced by more conventional airliners.
The following is a list of interned B-17s converted as commercial transports in Sweden:
Swedish registrations Designation Ex-USAAF Serials SE-BAH B-17F-75-DL 42-3543 SE-BAK B-17F-115-BO 42-30661 SE-BAM B-17G-5-BO 42-31163 SE-BAN B-17F-70-DL 42-3490 SE-BAO B-17G-40-BO 42-97115 SE-BAP B-17G-35-BO 42-32076 SE-BAR B-17G-35-DL 42-107067
SE-BAR and SE-BAP were sold to the Danish air line DDL in late 1945 as OY-DFE and OY-DFA respectively. In 1948, OY-DFA was sold to the Danish Army Air Corps under the serial number 67-672. In 1949, it was transferred to the Royal Danish Navy, and in 1952 it was transferred to the Royal Danish Air Force. It operated with the RDAF under the serial number ESK-721 and was used for transport, mapping, and communication. It was placed in storage in late 1953. In 1955, the Danish Air force finally sold the aircraft to the French Institut Geographique National (IGN), which added the plane to its fleet of B-17s that flew world-wide photographic and geophysical survey missions. Its French civil registration number was F-BGSP. It eventually ended up derelict, sitting out in the open as it was slowly scavenged for spare parts. In 1972, the USAF Museum purchased it and returned it to the US. It was restored in its original markings (with the nose art "Shoo Shoo Shoo Baby") and put on display at the Wright-Patterson AFB museum at Dayton, Ohio. I saw it there in 1992.