Republic Seabee Engine Conversions

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Most Seabee owners and pilots agree that one of the few weak points of an original RC-3 Seabee is the lack of engine power.  The original engine installation was a 215 hp Franklin Model 6A8-215-B8F/-B9F six cylinder engine.  The Seabee is a large airplane and with the Franklin engine the power-loading is quite high.

The huge cabin of the Seabee invites pilots to overload the airplane, and on a hot day a heavy loaded Franklin-powered Seabee will be a challenge to get in the air...

Simuflight Lycoming GO-480 Engine Conversion
Photo: © Mark Becker

Engine conversions therefore have been among the most popular of the many modifications developed for the Seabee, after production ceased in 1947.   Many experimental one-of-a-kind engine installations have been developed, including gas turbine engines.  Some of the engine conversions have been STC'ed and are offered commercially by a few companies.  The Lycoming GO-480 geared engine conversions have become the most popular.  However, the Lycoming GO-480-series engines are no longer in production (since 1979).  Direct drive Lycoming IO/TIO-540 engine conversions have also been installed on a number of Seabees.   The O-540-series engines are still in production at Lycoming.

TAC Lycoming IO/TIO-540 Engine Conversion
Photo: © Randy Komko

The newest Seabee engine conversions to emerge are the Robinson V8 engine conversions, developed by Mr. Brian Robinson in Canada.  The Robinson conversions utilize a 320 hp LS-1 or a 350 hp LS-6 Corvette G.M. V8 engine.

Twenty-three Seabees have been converted to twin engine configuration, through the STOL UC-1 Twin Bee conversion.  Actually, the Twin Bee conversion is so extensive that it requires a new Aircraft Type Certificate.

Franklin Standard Engines

 

W.S.K. - PZL-Rzeszow Ul. Hetmanska 12 PL-35 078 Rzeszow Poland

The original engine installation on manufacture at Republic in 1946/47, was the 215 hp Franklin 6A8-215-B8F/B9F six cylinder.   The RC-3 prototype / pre-production aircraft originally had a Model -B7F installed.  The Type Certificate for the Franklin engines is currently held by a Polish company.

Continental IO-470-P Engine Conversions

 

N6432K (#682)
George Pappas Continental IO-470-P engine conversion
Photo: © courtesy of Nancy and Randy Rhodes

In the late 1960s, expert mechanic and world class metal craftsman George Pappas installed a 250 hp Continental IO-470-P engine in his Seabee N6432K (MSN 682) in Anchorage, Alaska, where Pappas owns a company called Aircraft Rebuilders.  Pappas also designed his special cowlings for the Continental conversion. His conversion also have a reversible propeller.

The original "Pappas" cowling was very sleek and beautiful, as shown in the above photo.  However, it seems that one of the later owners modified the cowling by widening the inlet, probably to improve cooling.

The Continental IO-470-P engine was originally installed on the Italian NARDI / SIAI-Marcehtti FN.333 Riviera amphibian.  The supply of IO-470-P engines is less than plentyfull and therefore this engine is quite expensive.  Actually the IO-470-P conversion has never been STCed.  However, at least four more Seabees are reported to have been modified with IO-470-P engines under 'experimental' category; N124AC (MSN 60), N6056K (MSN 231), N6668K (MSN 945) and N6747K (MSN 1035). 

'Daubenspeck' Engine Conversions

 

STC Bee, Inc. 10900 Rainier Avenue S. Seattle, WA 98178 USA

In the late 1960s engineer and Seabee owner Jack Daubenspeck, Seattle, Washington, started to develop Seabee modifications.  Daubenspeck soon formed the company Aerocraft Inc. and initially designed, produced and marketed some very popular fiberglass 'droop' wing tips for the Seabee.  He also started the design and development of new Seabee engine conversions utilizing the Lycoming GO-435/GO-480 geared engines. 

At some stage of the development, Aerocraft Inc. started accepting predelivery deposits from eager Seabee owners who wanted to give their Seabees 'new' power. Unfortunately, engineering problems continued and the company was forced to close down when some of the Seabee owners lost their patience and wanted their deposits back.  The prototype 'Daubenspeck' Seabee was sold to cover the claims, and was never flown with the Lycoming engine under Daubenspeck's ownership.

Seabee owner John Greeff did not loose confidence in Daubenspeck and contracted him to finish the Lycoming GO-435/GO-480 engine conversion for his Seabee, N6456K (MSN 707).  With Mr. Greeff funding the company, Greeff and Daubenspeck started the company 'STC Bee, Inc.' to produce and market Daubenspeck's Seabee modifications.  

For the ' Daubenspeck' engine conversion a new "scoop type" glas fibre cowling was designed.  Most Daubenspeck conversions will be recognized by this beautiful cowling.  However, it is generally agreed that the 'Daubenspeck' cowling is heavier (55 lbs vs 22 lbs) and less maintenance-friendly than the 'Simuflight' cowling.

The Daubenspeck Lycoming GO-435/GO-480 engine conversions were FAA approved on 13 April 1976.  Originally the 1976 FAA STC # SA-282-NW was issued for the Lycoming GO-435-series with 260 hp, the GO-480B-series producing  270 hp on 80/87 octane fuel, the GO-480F-series producing  275 hp on 80/87 octane fuel; and the GO-480C/G-series which puts out 295 hp on 100/130 octane.  Approval is for engines with rear mounted accessories and either splined or flanged output shafts.  Propellers for all approved engines are 84" diameter, three blade, constant speed and reversible.  Fabricated sheet metal parts for the STC kits were manufactured by Robertson (STOL) Aircraft.

STC Bee, Inc. went out of business in 1985, and Mr. Daubenspeck died year 2000.   In May 2004 it is reported that Jack's son, Mr. John A. Daubenspeck is working on re-introducing the 'Daubenspeck' conversions and modifications.

STC Bee held the following STC for engine conversion:

STC No: SA282NW - Installation of Lycoming GO-480-B1D (270 hp @ 3400 RPM), GO-480-G1D6/G2D6 (295 hp @ 3400 RPM) engine and Hartzell HC83X20-2CL propeller. [Issued 1976-04-13].  

Robinson V8 Engine Conversions

 

Mr. Brian Robinson Eric B. Robinson Ltd. 12 Hardwood Street, RR#3  Kirkfield, Ontario KDM 2B0 Canada Tel: 715-340-2408 brian@v8aircraft.com  www.v8seabee.com

The Robinson engine conversion is the newest on the market, and has stirred a huge interest among Seabee owners.  Developed by Canadian Brian Robinson, the conversion utilize a Corvette V8 automobile engine mated to a cast aluminum reduction drive designed specifically for the Seabee..  To date the Robinson's have developed & flown the 320 hp LS1 version & the 350 hp LS6 version.  Late 2005 the new 350 hp LS2  and 400 hp LS7 versions were installed in the first Seabees.

The conversions have been successfully flown using both standard Seabee 2 and 3 blade propellers and modern 4 blade MT propellers.  Robinson has also developed a system which uses the Hartzell constant speed reversible propeller from a GO-480 powered Seabee.

The engine can use both premium unleaded automotive fuel and 100 LL aviation fuel.

Photo:	Registration:	MSN:	Engine:	Remarks:
	N48VP N46PH	001	LS6 (405 HP)	"Lake Tahoe Special" Steve Lantz. Crashed 2011-01-21. Ex RC-3 Seabee MSN 550
	CF-EVE	003	LS6 (350 HP)	Ex C-FZYL. "Robinson Special" 2009 André Durocher.
	C-FCBV	006	LS?	Frederick Robinson
	CF-EJE	71	LS2 (350 HP)	Planned conversion.
	N87525	82	LS6 (350 HP)	Under restoration. Robert Fudald.
	C-FHHS	281	LS7 (400 HP)	Under restoration. Donald Bradshaw.
	C-FGZX	593	LS2 (??? HP)	"Beeboyz Seabee".
	C-FDLS	627	LS1 (320 HP)	Cancelled as "destroyed". Probably became another "VeeBee"...
	C-GHQU	001 (639)	LS6	"SeaBeast LS6". Neil & Janet Kennedy. Flying.
	N6466K	717	LS?	Under restoration.
	N64PN	749	LS7	"Seabee Warbird" Peter Norman. Flying.
	C-GLYI	001-23-007 (793)	LS6 (310 HP)	"VeeBee - Amphibian" 2007 Ken Kunz. Ex CF-DKJ, N378NK. Flying.
	CF-WCB	815	LS2 (350 HP)	Under restoration.
	CF-ILM	001 (881)	LS1 (320 HP)	Prototype. "Robinson Special" 2007 Flying.
	C-FDOQ	02 (934)	LS6 (350 HP)	"Robinson Special" 2005 Mike Lush. Flying.
	C-FOME	001	LS1 (320 HP)	"Thunderbee" 2010 Buzz Hale Flying.
	C-FNMF	001 (887)	LS?	"Foster XB" 2013 Steven Foster Flying
	CF-GAD	965	LS?	"Seabee" 2002 Henry Chapeskie. Flying.
	C-GVEB	01	LS?	Manfred Loos "Seabee Special" 2020

Robinson V8 Engine Conversion
Photo: © Brian Robinson

August 2005:

Brian Robinson reported that interest in the V8 powered Seabee continued to grow. Seven converted Seabees were flying, and four more were under conversion. The first U.S. licensed V8 powered Seabee is the "Tahoe Special". Rebuilt from the ground up by Steve Lantz & Paul Shepard, the Tahoe Special is powered by an LS6 coupled to a four-blade MT reversible propeller. The aircraft won the Grand Champion Seaplane award at EAA Airventure 2005 in Oshkosh! Based at Carson, City Nevada, they often fly from land or water with density altitudes in the 9000’ range. Steve & Paul consider the air conditioning essential for operating in their climate.

Total fleet time is approximately 1800 hrs.  The highest time V8 Seabee is Brian's own airplane CF-ILM.  It has accumulated 1176 hours.  The longest trip has been from Balsam Lake to Key West Florida and return.  They use whatever fuel is available, automotive or aviation. The aircraft continues to perform flawlessly. The V8 installation has been operated from sea to level to 10,000 ft, and in temperatures ranging from -20°F to 113°F.

November 2014:

We flew the original installation 2,098 hours in the period from 4 July 2000 to 23 Dec 2011. During that time the aircraft performed far above my expectations. The engine and PSRU was performing well when it was removed. We removed it because my system was becoming dated. My aircraft was the first V 8 conversion done. It was running an LS 1 with a manual throttle standard Seabee Hartzell 3 blade propeller and our 1.68:1 reduction ratio. Most of my customers use the 1.98:1 ratio with an electric throttle. The Bee had a conventional (dated) panel and was in need of some upgrading. We refurbished ILM with many improvements including a new LS 3 sporting a modified Edelbrock supercharger, a new design single leaver control system that combines throttle, pitch, reverse & supercharger control functions in one unit, and a new design data link that allows the engine data to be sent directly from the engine control unit to the new MGL IEFIS based panel. The data link avoids the hassle of wiring in engine sensors and has the benefit of letting the pilot monitor the actual GM engine sensors that control the engine.  We were back in the air 14 Jan 2014 and now have 99 hours on the new installation. I am really happy with the  performance of the new engine and associated systems. I am sure ILM is one of most highly modified Seabee ever flown. The list of modifications are as follows: (Ed: too long to list here, see C-FILM ) I have not documented any performance numbers. For them to mean anything I would have to calibrate all the instruments & standardize the data. Sufficient to say I have flown ILM in side by side comparisons with many Seabees, and none of them have come close to matching the performance. The LS 3 is a noticeable improvement over the LS 1. I have only had the new engine to 10,000’ but I was able to still pull 30” HG. Someday I will borrow an oxygen system and explore the higher elevations. These days my focus has shifted from the Seabee to trying to raise capital to build the prototype of our new Horizon X2 - the first amphibian you can land on the water with the wheels down without hurting yourself! Visit our website www.V8Seabee.com and check out the Conversion Kits/Current status and Horizon X2 tabs for more pictures and information. Regards Brian E-mail dated November 21, 2014

The Robinson Horizon X2 The Next Generation Seabee!

 

USA Licensing Options

In the U.S. the only viable licensing option Robinson has been able to identify is compliance with the amateur built rules. In theory the aircraft could be licensed by using a one time STC or via the 337 processes. We have been unable to find an inspector willing to do this. The amateur built process is as follows

You currently cannot take a certified aircraft & license it as an amateur built aircraft. You can however build an amateur built aircraft using mostly certified aircraft components. This is only practical if the airframe is going to be refurbished. The process begins by removing the Manufacturers nameplate & ensuring the aircraft has been removed from the registry. You must then simply comply with the "51%" rule checklist. The only confusing part is that the 51% checklist has nothing to do with 51% of the work being done. It is simply a scorecard. You the owner must complete 51% of the items on the FAA approved checklist. There have been several Cessna 185 & 206 "replicas" built & licensed as amateur built aircraft. These aircraft are eligible for export to Canada & are permitted to cross the border. You may also import a Canadian amateur built aircraft into the U.S. It is important to note you cannot call the aircraft a Seabee. It must be called something else, e.g. A Robinson V-8 powered Bee. The name Seabee refers to a certified aircraft. If you call the FAA & tell them you are going to build an amateur built Seabee you will be turned down. If you call the FAA & tell them you are going to build a Robinson V-8 powered Bee (or any other name of you're choice) - an all aluminum, V-8 powered amphibian using modified Seabee components - they will inform you that you must comply with the 51% rule and instruct you to complete a 51% evaluation sheet. If your project meets the 51% criteria, it will be eligible for registration as an amateur built aircraft. The checklist is found on the FAA web site.

Robinson V8 Engine Conversions
C-FDOQ (MSN 934), CF-ILM (s/n 881) and C-GHQU (s/n 639)
Photo: © Brian Robinson

Below is a description of the protoype LS1 installation as installed on Robinson's Seabee CF-ILM.

Engine - The LS1, Corvette version, was a stock unit as purchased new from GM. It is rated at 345 HP @ 5600 RPM and produces 350 ft lbs torque @ 4400 RPM. The engine has been mated to a custom built 1.7:1 reduction unit. The engine was de-rated to approximately 320 HP by limiting the engine to 4500 RPM. This permitted the prop to turn @ 2600 RPM. (Maximum rating for the Hartzell Propeller installed on CF-ILM).  Robinson believed that de-rating the engine should help him reach his number one objective - reliability.  A large engine working at less than maximum power should last significantly longer than a small engine that is working it's heart out...

The engine was equipped with stock Corvette exhaust manifolds, machined to remove excess weight and mated to dual stainless steel mufflers. The mufflers and pipes were insulated reduce the heat buildup under the cowling.

The electric throttle body actuator was removed and replaced with the cable controlled mechanical throttle body actuator (KISS).

The engine was equipped with the stock GM air conditioning compressor.

The stock alternator was lowered to the same position used on the Camaro version of the LS-1 to provide clearance for the stock Seabee cowlings.

Reduction Unit - The reduction drive was custom designed to fit the Seabee installation using AutoCAD. It is based on standard Morse Hi VO chain and sprockets, and was sized and installed as per their technical publication. The chain is lubricated with engine oil via a spray bar.  Morse does not condone the use of their product in aircraft. The aluminum housing was cast, aged and tempered in a local foundry. All machining was done locally on a milling machine equipped with a digital readout. The design was loosely patterned off of the existing Franklin engine extension, with changes as required to maintain the existing thrust line and propeller position.

All thrust loads (forward and reverse) are carried by the rear reduction unit bearing. This is a copy of the Franklin setup and the thrust bearing used is the same as the original. The propeller pitch control system is identical to the Franklin set up. It has proven to be trouble free over the years. Oil return is by gravity to the engine sump, and all oil is filtered through a custom remote oil filtering system. The drive mates to the engine via a splined adapter bolted directly to the flywheel.  The heavy manual version of the flywheel was used as a safeguard against any potential vibration concerns.

Cooling System - The liquid cooling is provided by a stock Corvette radiator, complete with stock electric cooling fans controlled by the computer.  A manual over ride switch for the fans was added so that the pilot can turn the fans on anytime he pleases. The stock air conditioning condenser is mounted in front of the radiator as it is in the Corvette.

Fuel - Fuel is supplied via manually controlled dual electric fuel pumps, complete with a water separator and dual automotive filters. Operating pressure range is 58 - 62 PSI.  The LS1 will run on either premium automotive fuel or 100 Low Lead aviation fuel.

Engine Control System - The system chosen was a standard GM system. The unit is programmed with the export code for leaded fuel and uses no oxygen sensors. This was to enable owner to run 100 octane Low Lead fuel as well as premium unleaded fuel. It also meets the KISS criteria. The emission and VAT codes are suppressed. The computer is stock GM. After much research and correspondence, the wiring harness was purchased from an after market supplier. This portion of the project was as time consuming as designing the reduction drive. Robinson learned that it is imperative for a project like this to purchase the factory (not after market) manuals for the engine and read them thoroughly. You have to decide what is acceptable practice, how you want your engine management system to work, and have the harness manufactured accordingly.

The option of installing a second (backup) computer was discussed with many individuals. The resulting opinion was that the computer used is extremely reliable. The risk of a total computer failure is probably in the same league as a crankshaft or timing chain failure. The installation of a second computer would make the wiring harness considerably more complicated and increase the risk of a wiring harness/switching circuit failure. In the Robinson installation, Computer Power is supplied from one of two full size batteries. The batteries can be manually isolated in case of an alternator failure. The computer power source is selected manually.

Wiring Harness - The harness must be integrated into the airframe. Robinson believes that the odds of a wiring harness failure are greater than the risk of a mechanical failure (and you probably will get less warning). The harness utilizes crimped and/or soldered terminals. A good quality crimper was purchased and mil spec terminals and wires were used throughout. Routing, visibility, protection and security of the harness were installation priorities.

Pratt & Whitney PT6A Turbine Engine

 

Mark Ward SkyMark Aviation Services David Saunders AviaDesign Services Inc.

The Sea Hornet conversion has a Pratt & Whitney Canada PT6A-20 turbine engine, turning a specially built Hartzell 3 blade full feather, reversing propeller.  The engine has been de-rated to 400 SHP.

The subject Seabee is registered on the Canadian Civil Aircraft Register as C-GNVS (MSN 465).  The listed owner is Mr. R. Wallace of Bellingham, Washington, USA.  However, the modifications and flight testing are reported to be taking place in California.  From the photos it is also seen that the Seabee has gotten a serious 'nose-job'!  Also noted are the struts on the tailplane. The Turbine Seabee project has been named The 'Sea Hornet'.

The people behind the Turbine Seabee project - Mr. David Saunders (Avaiadesign Inc.) and  Mr. Mark Ward (SkyMark Aviation Services/AviaDesign Services Inc) - report that they already have accumulated a few hours on the 'Sea Hornet' and no problems have been experienced so far.  The Sea Hornet was also modified to get sponsons replacing the wing floats for water stability.  However, this modification was abandoned before completed.

C-GNVS (MSN 465)
PWC PT6A-20 Turbine Engine
Photo: © via Bruce Hinds

Simuflight Engine Conversions

 

Scott A. Henderson McHugh Aviation Inc. 3763 Image Drive Anchorage, Alaska 99504 Phone: 907.337.2860 Fax: 907.333.4482 scott@finite-tech.com www.simuflight.net

The most popular of all Seabee engine conversions available is undoubtedly the Simuflight Lycoming conversions.  Developed by Joe McHugh, the Simuflight conversions represent the majority of all Seabee engine conversions installed.  Sadly Joe McHugh was killed as a passenger in an airplane accident on 16 June 2003.

In August 2003, Mr. Scott A. Henderson, announced that he and his sisters intend to continuing the legacy of their father Joe McHugh, as soon as the estate is sorted out.  They expect to be back in operation beginning in February 2004. Simuflight will be merging with KenAir Aviation Co. of Sonoma, CA, (Ken Thompson) and will be building a new facility in Fallon, Nevada. The plan is to offer complete Seabee maintenance and restoration at the new facility.  Restoration and maintenance work is scheduled to begin on 1 October 2004.

Simuflight has a huge inventory of Seabee parts along with all the kits that Joe McHugh developed through the years. McHugh salvaged every Seabee part he ever came across through the years and if you can't find it in Simuflight's inventory, then it most likely doesn't exist any longer.  Simuflight also have a number of critical parts that McHugh invested in having remanufactured before the originals were lost forever.

Simuflight will also be completing a number of STC's that McHugh had started but never finished. Seabee owners that need parts and kits are encouraged to make orders now, so that Simuflight can ship them before they move to Fallon.

All inquiries should be forwarded to the above contact information.

Both the STC Bee (Daubenspeck) and Simuflight Lycoming engine conversion utilize the the GO-435 and GO-480 engine series. The geared Lycoming GO-480 engine allows a reduced propeller speed, 2170 rpm at engine speed of 3400 rpm, with reduced noise as a result. Data for the GO-480 engine can be found above. Due to the higher mount of the Simuflight engine conversion, larger propeller diameters can be installed on the Simuflight (89")  conversions than on the Daubenspeck (84") conversions.

T.A.C. Engine Conversions

 

Transition AirCraft, Inc. P.O. Box 285 McKenna, WA 98558 USA Tel: 360-458-7715 www.seabee-transition.com joekomo@hotmail.com

Owned by Mr. Randy M. Komko, Transition AirCraft, Inc., (TAC), has developed the Lycoming IO-540 (250 - 300 hp) and Lycoming TIO-540 (300 - 350 hp) 'direct drive' engine conversions for the Seabee.  The TAC conversions utilize the 'Daubenspeck'-type cowling.   

In co-operation with other parties, Mr. Komko has also been involved in the development, installation and flight-tests of a number of GO-480-series engine conversions since 1976, including the the first GSO-480 (340 hp) Seabee engine conversion installed (N6124K MSN 310 flying on 1983-10-08).

Here is a list of some of the "TAC" Seabees:

Photo	Reg. No:	MSN:	Year:	Engine:	Remarks:
	N66CB	774	1976	GO-480	TAC # 1
	N6684K	967	1976	GO-480-G1B6 295 HP	TAC # 2
	N37619	599	1979		TAC # 3 Rebuilt after 15 years under water.
	N6119K	305	1980	IGSO-480	TAC # 4
	N87576	143	1980	GO-480	TAC # 5 Wreck purchased by TAC after crash in 1980. Under rebuild.
	N6014K	184	1993	GO-480	TAC #6 Rebuilt by TAC after crash 1993.
	N3500G N129JS	631		TIO-540-A2B 350 HP	SA5652NM
	N6522K	788		IO-540
	N6267K	477	1999	TIO-540-A2B 350 HP	SA5652NM
	N6144K N5YL	330		GSO-480-B1G6 340 HP	SA5734NM
	N6286K	499		TIO-540-A2B  350 HP	SA5652NM
	N6381K	610		IO-540  300 HP @ 2700 RPM	SA5652NM
	N6585K	858		IO-540 300 HP @ 2700 RPM	SA5652NM
	N6723K	1006		GO-435-B2C2	Crashed 2003.  Wreck purchased by TAC.
	N245RC	245	2006	GSO-480 340 HP
	N6290K	503	1994?	IO-540-K 300 HP @ 2700 RPM	SA4330NM
	N6124K	310	1983	GSO-480 340 HP?
	N447ZK	517	2012	IO-540 300 HP	Ex CF-EJK. MT Propeller.

Randy also offer several other Seabee modifications; including 6 place interior, droop wingtips, new wing floats, new spray rails.

TAC holds the following engine conversion STCs:

STC No: SA5652NM - Installation of a Lycoming TIO-540-A2B engine together with a Hartzell HC-E3YR-7LF/FLC8468-4R propeller.  [STC reissued 1992-03-31].

STC No: SA4330NM - Installation of a Lycoming IO-540-K engine (N6290K).

Turbomeca Astazou II Turbine Engine

 

Clark Cameron Robert A. Mael Canada Experimental

The Turbomeca Astazou II L turboprop engine installation on Seabee CF-MYT (MSN 1025) was engineered for owner (?) Bernard Robillard, Montreol, Canada, by Robert A. Mael; Northeast Engineering and Development Ltd. during the late 1970ies.  The installation was completed on 7 October 1980.

Turboprop Seabee CF-MYT (MSN 1025)
Balsam Lake, Ontario, Canada
Photo: © Blair Robinson

After skis had been installed on the Seabee early in January 1982, the Turbine Seabee made her first flight on 15 January 1982 with pilot/owner Clark Cameron at the controls.  Several test flights were made during January/February, achieving speeds in excess of 155 mph at 95% power, rate of climb 2700 ft/min at 100% power and fuel consumption of 12 US gal per hour at 55% power and cruise speed of 110 mph.

Mr. Blair Robinson kindly supplied the following additional information:

These photographs were taken at fathers dock on Balsam Lake, Canada.  Clark was a close friend of the family, & his Bee was based on Canal Lake, several miles from dads... This Seabee was designed, built & flown by the late Clark Cameron. He passed away suddenly walking away from the Bee after a test flight on skis. The airplane changed hands several times after his passing, but to my knowledge has not flown since Clark’s last flight.

I have many fond memories of the Ontario Seabee club meetings which were held at Clark’s house. He would often entertain the group by firing up the engine which was mounted in a test stand chained to his well to prevent it from moving. The engine was a Turbomeca Astazou. It was extremely noisy, his neighbors must have loved him! Many club meetings were spent debating the design concepts. If my memory serves me correct the engine was rated at 450 HP. Clark promised the DOT he would de-rate the engine to 250 HP. He was never able to figure out how to de-rate the engine and flew it with the full 450 HP. Clark owned his own machine shop and manufactured most of the components himself.

One of the pictures shows Clark in the middle, our dad Eric Robinson on the right and I am on the left. The day that these pictures were taken both dad and I flew Clark’s Seabee. Unfortunately Clark passed away early the following year. He proved the airplane would fly but never got the opportunity to complete the project or solve some of the issues such as hot starts, prop control, excessive noise and severely limited range. The airplane was operated under an experimental certificate only. My brother snapped these pictures with his Polaroid camera, we wish we had more...

CF-MYT is currently (since 1994-09-26) owned by Mr. Jean-Marc Rochette; 1905 Rte Du Domaine, St-Raymond, Quebec G3L 3A5, Canada.

Specifications - Turboméca Astazou II L
Manufacturer	Société Turbomeca
Address	Bordes, F-64320 Bizanos, France
Model	Astazou II L
Type	Single-shaft axial-plus-centrifugal turboprop
Approved Type Certificate No.	?
Weight - dry	348 lbs
Rated Power (T/O)	523 shp
Maximum Continuous	475 shp
Rated Turbine Speed (T/O)	43 500 rpm
Maximum Continuous Speed	43 500 rpm

W. E. Aerotech Engine Conversions

 

W. E. Aerotech Services West 171 Sanderson Way Shelton, WA 98584 USA

W. E. Aerotech Services was run by Mr. Donald 'Don' Wallace and Mrs. Deborah Wallace Aerotech 'remanufactured' a number of Seabees until year 2000, when the company went out of business.  They also had under development a Continental IO-520 engine conversion.

STC No: SA00332SE - Installation of a Lycoming GSO-480-B2C6 engine (340 hp @ 3400 rpm) and Hartzell HC-A3CF-23L reversible propeller [Issued 1996-04-26].

Cukurs Engine Conversions

 

Gunars Cukurs Brazil

In Brazil Mr. Gunnar Cukurs operated several Seabees for more than 4 decades. During those years at least two one-of-a-kind engine conversions were developed by Cukurs and tested on the Seabees.  When the crankshaft of one the Franklin engines broke, the Franklin engine was replaced by an Argus AS10C engine from a pre-WW2 Focke Wulf 56 aircraft!  The engine had a power of 240 hp at 2000 hp.  Later a Lycoming GO-435 engine was installed from a Pilatus PC3 aerobatic aircraft.  Finally the now common GO-480-G2D6 engine conversion was installed.

Argus AS10C engine installation
Photo: © via Richard Cukurs

Lycoming GO-435 (?) engine installation
Photo: © via Richard Cukurs

Republic Seabee Conversions Installed

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