Beechcraft Model 18

, 1986 , France By the late 1930s, Beechcraft management speculated that a demand would exist for a new design dubbed the Model 18, which would have a military application, and increased the main production facilities. The design was mainly conventional for the time, including twin radial engines, all-metal semimonocoque construction with fabric-covered control surfaces, and tailwheel undercarriage. Less conventional was the twin-tailfin configuration. The Model 18 can be mistaken for the larger Lockheed Electra series of airliners, which closely resemble it. Early production aircraft were powered either by two 330-hp (250-kW) Jacobs L-6s or 350-hp (260-kW) Wright R-760Es. The 450-hp (336-kW) Pratt & Whitney R-985 "Wasp Junior" nine-cylinder radial engine became the definitive powerplant from the prewar C18S onwards. The Beech 18 prototype first flew on 15 January 1937, and type certification followed on 4 March that year. The Model 18 has used a variety of engines and has had a number of airframe modifications to increase gross weight and speed. At least one aircraft was modified to utilize 600-hp (447-kW) Pratt & Whitney R-1340 "Wasp" powerplants. With the added weight of about 200 lb (91 kg) per engine, the concept of a Model 18 fitted with R-1340 engines was deemed unsatisfactory due to the weakest structural area of the aircraft being the engine mounts. Nearly every airframe component has been modified. In 1955, deliveries of the Model E18S commenced; the E18S featured a fuselage that was extended higher for more headroom in the passenger cabin. All later Beech 18s (sometimes called Super 18s) featured this taller fuselage, and some earlier models (including one AT-11) have been modified to this larger fuselage. The Model H18, introduced in 1963, featured optional tricycle undercarriage. Unusually, the undercarriage was developed for earlier-model aircraft under an STC by Volpar, and installed in H18s at the factory during manufacture. A total of 109 H18s was built with tricycle undercarriage, and another 240 earlier-model aircraft were modified with this. Construction of the Beechcraft Model 18 ended in 1970 with a final Model H18 going to Miyazaki Aviation College, Japan. Through the years, 32 variations of the basic design had flown, over 200 improvement modification kits were developed, and almost 8,000 aircraft were built. In one case, the aircraft was modified to a triple tail, trigear, humpbacked configuration and appeared similar to a miniature Lockheed Constellation. ==Operational history==

Production got an early boost when Nationalist China paid the company US$750,000 for six M18R light bombers, but by the time of the U.S. entry into World War II, only 39 Model 18s had been sold, of which 29 were for civilian customers. The Navy subsequently obtained more Model 18s as the JRB-3 (C-45B), JRB-4 (UC-45F), SNB-1 Kansan (AT-11), SNB-2 (AT-7), and SNB-2C (AT-7C). Existing naval Twin Beeches were subsequently modified into the SNB-2H air ambulance, SNB-2P reconnaissance trainer, and SNB-3Q electronic countermeasures trainer. The United States Coast Guard acquired seven JRB-4 and JRB-5 aircraft from the Navy between 1943 and 1947; they were primarily used as utility transports, with one aircraft later converted for aerial mapping, and another used for proficiency flying. After the war, the USAAF became the United States Air Force (USAF), and the USAF Strategic Air Command had Model 18 variants (AT-11 Kansans, C-45 Expeditors, F-2 Expeditors, and UC-45 Expeditors) from 1946 until 1951. In 1950, the Navy still had around 1,200 JRB and SNB aircraft in inventory. From 1951 to 1955, the USAF had many of its aircraft remanufactured with new fuselages, wing center sections, and undercarriages to take advantage of the improvements to the civil models since the end of World War II. Eventually, 900 aircraft were remanufactured to be similar to the then-current Model D18S and given new designations, constructor's numbers, and Air Force serial numbers. The USN had many of its surviving aircraft remanufactured as well, resulting in the JRB-6, the SNB-5, and SNB-5P. The Coast Guard retired its JRBs in 1956 and sold most of them as surplus in 1959, but one was retained by the United States Coast Guard Reserve until at least 1972. Beech 18s were used extensively by Air America during the Vietnam War; initially more-or-less standard ex-military C-45 examples were used, but then the airline had 12 aircraft modified by Conrad Conversions in 1963 and 1964 to increase performance and load-carrying capacity. The modified aircraft were known as Conrad Ten-Twos, as the maximum takeoff weight (MTOW) was increased to . The increase was achieved by several airframe modifications, including increased horizontal stabilizer angle-of-incidence, redesigned undercarriage doors, and aerodynamically improved wingtips. Air America then had Volpar convert 14 aircraft to turboprop power, fitted with Garrett AiResearch TPE-331 engines; modified aircraft were called Volpar Turbo Beeches, and also had a further increase in MTOW to . Spar problems The wing spar of the Model 18 was fabricated by welding an assembly of tubular steel. The configuration of the tubes in combination with drilled holes from aftermarket STC modifications on some of these aircraft have allowed the spar to become susceptible to corrosion and cracking while in service. This prompted the FAA to issue an Airworthiness Directive in 1975, mandating the fitting of a spar strap to some Model 18s. This led, in turn, to the retirement of a large number of STC-modified Model 18s when owners determined the aircraft were worth less than the cost of the modifications. The corrosion on unmodified spars was not a problem; it occurred due to the additional exposed surface area created through the STC hole-drilling process. Further requirements have been mandated by the FAA and other national airworthiness authorities, including regular removal of the spar strap to allow the strap to be checked for cracks and corrosion and the spar to be X-rayed. In Australia, the airworthiness authority has placed a life limit on the airframe, beyond which aircraft are not allowed to fly. ==Variants==

Manufacturer models Unless otherwise noted, the engines fitted are Pratt & Whitney R-985 radials. ;Model 18A :First production model with seating for two pilots and seven or eight passengers, fitted with Wright R-760E-2 engines of , MTOW: • Model S18A :Version of Model 18A capable of being fitted with skis or Edo 55-7170 floats; MTOW: ;Model A18A :Version fitted with Wright R-760E-2 engines, MTOW: Twelve aircraft built. ;Model B18S :Nine-passenger pre-World War II civil variant, served as basis for USAAF F-2 ;Model D18S :First post-World War II variant introduced in 1945, with seating for eight passengers and MTOW of , 1,035 built ;Model D18C :Variant with Continental R9-A engines of and MTOW of , introduced in 1947, 31 built. ;Model E18S :Variant with redesigned wing and MTOW of ; 403 built ;C-45A :Eight-seat utility transport based on C18S; ;C-45C :Two Model 18S aircraft impressed into the USAAF, redesignated UC-45C in January 1943 ;C-45D :Designation given to two AT-7 aircraft converted as passenger transports during manufacture, redesignated UC-45D in January 1943 , Platte Valley Airpark, Hudson, Colorado, June 2007 ;C-45E :Designation given to two AT-7 and four AT-7B aircraft converted as passenger transports during manufacture, redesignated UC-45E in January 1943 ;C-45H :AT-7s and AT-11s remanufactured in the early 1950s for the USAF to similar standard as civil D18S, with no autopilot and R-985-AN-14B engines; 432 aircraft rebuilt ;TC-45H ;AT-11A :Conversion of AT-11 as navigation trainer; 36 converted at least one conversion from impressed civil B18S some transferred from USAAF C-45A stocks ;JRB-3 :Photographic version, similar to C-45B; 23 obtained, ;JRB-6 :Remanufactured JRB ;SNB-1 :Similar to AT-11; 110 built ;SNB-2 :Navigation trainer similar to AT-7, 299 built ;SNB-2C :Navigation trainer similar to AT-7C, 375 built ;SNB-2H :Ambulance conversion ;SNB-2P :Photo-reconnaissance trainer conversion ;SNB-3Q :Electronic countermeasures trainer conversion ;SNB-5 ;SNB-5P ;Expeditor 3N: navigation trainer – 88 built ;Expeditor 3NMT: 3NM converted to a transport aircraft – 67 built ;Expeditor 3NMT(Special): navigation trainer/personnel transport – 19 built ;Expeditor 3TM: transport with fittings so it could be converted to a navigation trainer – 44 built ;Expeditor 3TM(Special): modified RCAF Expeditors used overseas in conjunction with Project WPB6 – three built Canadian Armed Forces ;CT-128 Expeditor: 1968 redesignation of existing RCAF aircraft upon unification of the Canadian Armed Forces Brazilian Air Force designations ;U-45 :Designation for the C-45. Royal Thai Air Force designations ;B.L.1 :() designation for the C-45B and C-45F. Conversions ;Conrad 9800 :Modification increasing the gross weight to 9,800 pounds with a single piece windshield ;Dumod I : Executive conversion with Volpar tricycle landing gear, new wing tips, enlarged fight deck and refurbished 6–7 seat cabin with larger windows. Originally named Infinité I. 37 converted by 1966. ;Dumod Liner :Stretched airliner conversion. Similar to Dumod I but with forward fuselage stretched by , allowing up to 15 passengers to be carried. Originally named Infinité II. ;Hamilton Westwind :Turboprop conversions with various engines ;Hamilton Westwind II STD: Stretched conversion powered by two 840-hp PT6As, and with accommodation for up to 17 passengers ;Hamilton Westwind III:two 579-hp PT6A-20s or 630-hp PT6A-27s or 630-hp Lycoming LTS101s. ;Hamilton Westwind IV:two 570-hp Lycoming LTP101s or 680-hp PT6A-28s or 750-hp PT6A-34s or 1020-hp PT6A-45s ;PacAero Tradewind :Conversion of Beech D18S/C-45 to five- to 11-seat executive transport with single fin by Pacific Airmotive ;Rausch Star 250 :Built as C-45F 44-47231, this aircraft was re-manufactured at Wichita by Beech in 1952, to become TC-45G 51-11544. From 1959 Rausch Engineering Inc. of South San Francisco, California, converted N8186H to tricycle undercarriage, using forward retracting main gear from a P-51 and rearward-retracting nose-leg from a T-28, adding a nose extension, rear fuselage extension, re-roofed fuselage for increased headroom and enlarged cabin windows. The modifications did not obtain FAA certification despite 58 hours of flight testing, with the aircraft eventually being broken up at Antioch, CA, in 1978. ;SFERMA-Beechcraft PD.18S :Modification of Beech 18S powered by two Turboméca Bastan turboprops ;Volpar (Beechcraft) Model 18 :Conversion of Model 18 with nosewheel undercarriage ;Volpar (Beechcraft) Super 18: ;Volpar (Beechcraft) Turbo 18:Beech Model 18s fitted with the Volpar MkIV tricycle undercarriage and powered by two 705-hp Garrett TPE331-1-101B turboprop engines, flat-rated to , driving Hartzell HC-B3TN-5 three-bladed, reversible-pitch, constant-speed feathering propellers ;Volpar (Beechcraft) Turboliner II :Turboliners modified to meet SFAR 23 ==Operators==

Civil , the Beechcraft Model 18 remains popular with air charter companies and small feeder airlines worldwide. Military C-45 for civilian aerial photography missions AT-11 SNB-4 ; • Argentine Air Force • Argentine Naval Aviation ; • Bolivian Air Force ; • Brazilian Air Force • Royal Canadian Navy 10 examples from 1952 to 1960 • VX-10 Squadron • VU-32 Squadron • Canadian Armed Forces ; • Chilean Air Force • Chilean Army • Chilean Navy ; • Colombian Air Force ; • Public Force of Costa Rica ; ; • Cuban Air Force - received two AT-7s, two AT-11s, a F-2B and a UC-45F in 1947 ; • Dominican Air Force ; • Ecuadorian Air Force ; • French Air Force ; • Haiti Air Corps ; • Indonesian Army ; • Japan Maritime Self-Defense Force • Japan Coast Guard ; • Mexican Air Force • Mexican Navy ; • Peruvian Air Force • Portuguese Navy ; ; • Sri Lanka Air Force ; • Swiss Air Force ; • Republic of China Air Force ; • Royal Thai Air Force ; • Tongan Air Wing ; • Turkish Air Force ; • Venezuelan Air Force ; • Zairian Air Force ==Accidents and incidents==

The Beechcraft Model 18 family has been involved in the following notable accidents and incidents: • 25 April 1951: Cubana de Aviación Flight 493, a Douglas DC-4 bound from Miami to Havana, registration CU-T188, collided with a U.S. Navy SNB-1, bureau number 39939, on a practice instrument approach to Naval Air Station Key West. The collision and ensuing crashes killed all 34 passengers and five crew aboard the DC-4 and all five crew aboard the SNB. The accident occurred at midday, weather was clear with unlimited visibility, and both flight crews had been cleared to fly under visual flight rules, being expected to "see and avoid" other aircraft; the student flying the SNB was wearing view-limiting goggles, but the other SNB crew were not, and were expected to keep watch. Ground witnesses said that neither aircraft took evasive action prior to the collision, and the Civil Aeronautics Board attributed the accident to the failure of both flight crews to see and avoid conflicting air traffic. • 1967: Mohammed bin Awad bin Laden was killed in the crash of a Beechcraft 18 in Saudi Arabia. • 10 December 1967: American soul music singer Otis Redding, four members of his backing band the Bar-Kays, the pilot, and another member of Redding's entourage were killed in the crash of Redding's H18, registration N390R, into Lake Monona on approach to Truax Field in Wisconsin. The National Transportation Safety Board (NTSB) was unable to determine the cause of the crash, noting that the left engine and propeller were not recovered. Trumpet player Ben Cauley, the sole survivor of the crash, subsequently revived the Bar-Kays together with another band member who was aboard a different aircraft. • 20 September 1973: American folk rock singer-songwriter Jim Croce, four members of his entourage, and the pilot were killed when their chartered E18S, registration N50JR, crashed into a tree shortly after takeoff from Natchitoches Regional Airport in Louisiana. An investigation conducted for a lawsuit against the charter company attributed the accident solely to pilot error, citing his downwind takeoff into a "black hole" of severe darkness, causing him to experience spatial disorientation. • 26 September 1978: Air Caribbean Flight 309, an air taxi flight by a D18S, registration N500L, crashed on approach to Isla Verde International Airport in Puerto Rico, killing the pilot and the five passengers aboard the aircraft and causing substantial property damage and injuries to bystanders on the ground. The pilot could not communicate with approach control and was following directions relayed by local tower controllers, who told the pilot to make a turn and maintain separation from a Lockheed L-1011 that was overtaking the flight, but the pilot did not turn, and the D18S passed underneath and very close to the L-1011. Both the NTSB and a U.S. District Court ruling attributed the crash to the D18S pilot's failure to correctly follow visual flight rules and air traffic control instructions to maintain separation from the much larger L-1011, causing a loss of aircraft control due to wake turbulence. A contributing factor was the pilot's difficulties in communication with controllers. The pilot performed an "abrupt" climb and performed a "hammerhead stall" maneuver, reversing direction and entering a dive. The accident was attributed to the pilot's poor judgment and failure to maintain altitude during unauthorized attempted aerobatics. ==Aircraft on display==

Argentina • 3495 – AT-11A at the Museo Nacional de Aeronáutica de Argentina in Buenos Aires. • 5621 – C-45H at the Museo Nacional de Aeronáutica de Argentina in Buenos Aires. • AF-555 – C-45H at the Museo Nacional de Aeronáutica de Argentina in Buenos Aires. • c/no. BA-752 (former LV-JFH) – H18S at the Museo Nacional de Aeronáutica de Argentina in Buenos Aires. Australia • c/no. BA-81 (former N3781B) – E18S at the Queensland Air Museum in Caloundra, Queensland. Belgium • c/no CA-191 (former C-FGNR) – 3NM at Pairi Daiza. Brazil • 4615 – AT-11 at the Museu Aeroespacial in Rio de Janeiro, Brazil. • 2856 – C-45F at the Museu Aeroespacial in Rio de Janeiro, Brazil. Canada • 459 – C-45H at the Canadian Bushplane Heritage Centre in Sault Ste. Marie, Ontario. Tail code CF-MJY • 8034 – 3TM at the Canadian Bushplane Heritage Centre in Sault Ste. Marie, Ontario. • c/no. A-141 (former CF-MPH) – D18S at the RCMP Academy, Depot Division in Regina, Saskatchewan. • c/no. A-142 (former CF-MPI) – D18S at the Bomber Command Museum of Canada in Nanton, Alberta. • c/no. A-156 – D18S at the Canadian Warplane Heritage Museum in Hamilton, Ontario. • c/no. A-652 (former RCAF 1477) – 3N at the Royal Aviation Museum of Western Canada in Winnipeg, Manitoba. • c/no. A-700 – 3NMT at the Canadian Air Land Sea Museum at Toronto/Markham Airport in Markham, Ontario. • c/no. A-782 (former CF-CKT) – 3NMT at the Canadian Museum of Flight in Langley, British Columbia. • c/no. A-872 – 3NMT at the TransCanada Highway in Ignace, Ontario. • c/no. A-895 – 3NM at the Alberta Aviation Museum in Edmonton, Alberta. • c/no. 92-074 – 3NM at The Hangar Flight Museum in Calgary, Alberta. Chile • c/no. A-1024 (former FACh 465) – D18S at the Museo Aeronautico y del Espacio in Santiago, Chile. India • VT-CNY – D18S former aircraft of the Raja of Mayurbhanj and later sold to Coal India Limited- at the Hotel Mayfair Lagoon in Bhubaneswar, Orissa. Italy • 6668 – C-45F suspended inside the Olbia Costa Smeralda Airport passenger terminal in Olbia, Sardinia. Japan • 'JA5174' – H18 the final Beech 18 produced (c/n BA-765), delivered January 1970 to Miyazaki Aviation College, Japan. In use until 1988, now preserved at the College, Miyazaki Airport. Mexico • "ETL-1320" (S/N): 18 – UC-45J at the Museo Militar de Aviación. Netherlands • 51-11665 – C-45G at the Aviodrome in Lelystad, Netherlands. New Zealand • 3691 – AT-11 at the Museum of Transport and Technology in Auckland, New Zealand. Portugal • 2504 – AT-11 at the Museu do Ar in Sintra, Portugal. Spain • AF-752 – C-45H at Fundación Infante de Orleans in Madrid, Spain. Turkey • 6390/9-930 – AT-11 at Istanbul Aviation Museum. United Kingdom • G-ASUG c/no. BA-111 – E18S at the National Museum of Flight in East Lothian, Scotland. United States • 41-27561 – AT-11 at the National Museum of the USAF in Dayton, Ohio. or 42-37493 • 42-36887 – AT-11 at the Barksdale Global Power Museum in Bossier City, Louisiana. • 42-37240 – AT-11 at the Lone Star Flight Museum in Galveston, Texas. • 42-37496 – UC-45 at the Wings Over the Rockies Air and Space Museum in Denver, Colorado. This aircraft was originally an AT-11 before being remanufactured. • 44-47342 – UC-45F at the Alaska Aviation Heritage Museum in Anchorage, Alaska. • 51-11467 – C-45G at the EAA Chapter 1241 Air Museum at the Florida Keys Marathon Airport in Marathon, Florida. • 51-11529 – TC-45H at the Tri-State Warbird Museum in Batavia, Ohio. • 51-11696 – C-45H at the Museum of Flight in Seattle, Washington. • 51-11795 – C-45G at the Air Mobility Command Museum in Dover, Delaware. • 51-11897 – C-45G at the Castle Air Museum in Atwater, California. • 52-10539 – C-45H at the 1941 Historical Aircraft Group Museum in Geneseo, New York. • 52-10865 – C-45H at the Travis Air Force Base Heritage Center at Travis AFB, California. • 52-10893 – C-45H at the National Museum of the USAF in Dayton, Ohio. • 09771 – UC-45J at the National Museum of Naval Aviation in Pensacola, Florida. This aircraft was converted from the last civil Beech 18 built prior to WWII. • 51242 – UC-45J at the CAF Central Texas Wing in San Marcos, Texas. • 51291 – UC-45J at the Aerospace Museum of California in Sacramento, California. • 51338 – UC-45J at the Minnesota Air National Guard Museum in St. Paul, Minnesota. • c/no. 178 – S18D at the Beechcraft Heritage Museum in Tullahoma, Tennessee. • c/no. A-935 – D18S at the Beechcraft Heritage Museum in Tullahoma, Tennessee. • AF-824 – C-45H at the Beechcraft Heritage Museum in Tullahoma, Tennessee. • c/no. BA-453 – E18S at the Beechcraft Heritage Museum in Tullahoma, Tennessee. • c/no. BA-670 – H18 at the Lone Star Flight Museum in Galveston, Texas. ==Specifications (UC-45 Expeditor)==