Baggage space normally totals 17 cubic feet butcan be nearly doubled by folding the rear seats.~balance has tipped in the 201's favor.In the past three years, Mooney sold305 Model 231s and 367 Model 201s.Mooney Aircraft and Teledyne ContinentalMotors had to make a decision:Make the TSIO-360 engine runcooler, or settle for increasingly cooler231 sales. They chose the former, ofcourse.The best solution to the heat problem,an intercooler, was rejected byMooney. An intercooler basically is aradiator that reduces the temperatureof induction air as it passes from theturbocharger compressor into the intakemanifold. Mooney felt that thebenefits of an intercooler would becompromised by its cost and increasedcomplexity.(An intercooler kit for the Mooney231 is available from Turboplus. Thekit includes an intercooler, intake ductsand an outflow plenum and costs$4,495. According to the company, 24hours of labor are required for installation.More information on the Turboplusintercooler kit can be obtainedfrom Turboplus, Incorporated, 1437West Valley Highway, Auburn, Washington98001; 206/735-2700 or 800/742-4202).Mooney chose, instead, to work withContinental on improving the flow ofair and fuel through the engine. Thediameter of the throttle body was increasedfrom 2.06 to 2.50 inches toprovide a larger passageway for inductionair and wider fuel-injection lineswere incorporated to facilitate fuelflow. Back pressure on the turbochargerwas reduced by reducing theoverboost (poppet) valve setting from44 to 41.5 inches. Back pressure alsowas reduced by eliminating a resonatorin the exhaust system. "The resonatorwas supposed to silence exhaust(loise," a Continental engineer said,"but it was not worth the back pressureit produced."The transformation of the TSIO360GB engine into the TSIO-360LB engineincluded several other refinementsworthy of mention. The cylinder wallsare now coated with zinc phosphate,which protects them from corrosionduring the time the engine is shippedfrom Continental, installed in an airplaneand delivered by Mooney. Thecoating is burned off within 25 hoursof engine operation.The cylinder walls also are impregnatedwith nitrite, a hardening agent;.and a cast steel compression ring guideAOPA PILOT • 27
continutdMOONEY 231lhas been incorporated in each piston.The guide prevents the ring from flutteringwhen the engine is operated atlow power settings. Nitriding and thenew ring guides are intended to improveengine wear characteristics. Inaddition, the alternate induction airsystem now operates automatically aswell as manually.The recommended time betweenmajor overhaul (TBO) of the TSIO-360engine remains 1,800 hours, but Mooneyand Continental, have increasedtheir warranty on the new LB enginefrom six months to one year.. Only time, and service difficulty reportssubmitted by 231 owners, willtell if Mooney and Continental haveimproved the heat-management problem.Our experience with N5737M indicatesthat the 231 now can be flownat the altitudes for which it originallywas designed.In addition to the new engine for the231, Mooney has introduced a numberof new features for both airplanes. Sixaccess panels on the bellies of bothmodels have been eliminated. Access2B. APRIL1984to fuel lines, control systems, fuel selectorand landing gear actuator now isachieved by removing an eight- Xthree-foot fiberglass panel that is heldin place by 38, quarter-turn fasteners.The unit also houses a marker beaconantenna.Cockpit instrumentation now is internallylit rather than post-lighted andincludes more accurate oil-pressure andfuel-pressure transducers. The manifoldpressure gauge has been reducedin size from three inches to two inchesto correspond with the compressor-dischargeand turbine inlet temperaturegauge and the tachometer. The smallermanifold pressure gauge also has freedmore room for the circuit breakerpanel.Drag has been reduced slightly witha Teflon seal for the nose gear doors, atailcone fairing, redesigned engine-accesshatches, elimination of both anair-induction port and a cabin vent onthe left fuselage and replacement of a"towel-bar" antenna with a blade antennaon the vertical stabilizer.A standby vacuum system is availableas an option for both the 231 andthe 201. The system weighs 12 poundsand includes an electric motor in thetail. Cost of the option is $1,850.Our evaluation airplane W.1S intendedto be a factory demonstrator(but was sold shortly after it was produced)and is very well equipped. KingSilver Crown avionics equipment, includinga KFC 200 flight control system,a Sperry WeatherScout colorweather radar, 3M Storms cope, TexasInstruments 9100 Loran receiver, 76cubic-foot oxygen system and propellerdeicing system were among the optionsthat brought the net price ofN5737M to $177,370 from the baseprice of $86,950 for a 1984 Model 231.The airplane also has a standby generatorsystem, an option introduced forthe 231, only, in 1982. A 14-volt directcurrentgenerator is mounted on an engineaccessory drive and is connectedto its own voltage regulator. Shouldthe alternator fail, the pilot can connectthe generator to the standby bus bypulling the circuit breakers for both thealternator and the battery. The standby
us powers the following equipment:the number one communications transceiverand navigation receiver; transponder;altitude encoder; headphonejack; fuel totalizer; gear and stall warningsystems; annunciator panel; engineguages; turn coordinator; horizontalsituation indicator; tachometer; andoutside air temperature gauge. The circuitbreakers for these systems aregrouped together on the panel. Othersystems-such as the landing gear,flaps and radio speaker-are not includedin the standby generator system.To activate these systems, themain bus must be connected to thebattery by pushingbreaker.the battery circuitThe Mooney 231 is, indeed, an electricairplane. (See "The Electric Airplane,"by Edward G. Tripp, June 1981Pilot, p. 107.) Operating a 231equipped as N5737M is (and as mostM20Ks are) requires judicious selectionof what you need to use and what canbe left on standby. A pilot just cannottum everything on and expect the alternatorto carry the load. It won't.When operating in instrument weatherconditions, the standby generator system(5.8 pounds and $2,700) is a goodoption to have, just in case.Although the airplane generally performedwell during our two-weeklease, it did exhibit a few teethingproblems. One Pilot editor reportedthat the weather radar system and theStormscope failed to provide any usefulinformation during one flight insome heavy weather. At high powersettings, the 231's throttle and propellercontrols required nearly constantadjustment. The Loran receiver did notfunction properly; a malfunctioningamplifier was the culprit. (Pilot willhave a full report on the TI 9100From fuel gauges to colorweather radar, almosteverything in the Mooney231's panel runs onelectricity. An optionalstand-by generator canprovide a hedge againstan alternator failure.Loran receiver in an upcoming issue.)The fuel filler caps were a constantheadache. They tend to stick if not lubricatedregularly (every week, atleast).When the cowl flaps are closed, thecabin heater is more than adequate tokeep the cabin toasty on a cold day butdischarges onto the fuel selector, makingit very hot to the touch. I learnedto protect my fingers with a handkerchiefwhile switching tanks.The biggest complaint, however, waslodged by a passenger. The rear seatsare uncomfortable on a long flight. Theseat pads are small and do not providemuch latitude for adjusting your position.The elbow rests are narrow andpractically useless, and the wing sparcarry-through structure chafes yourcalves, if you happen to be short instature. (The front seats are quite comfortable,though.)In my opinion, these shortcomingsdo not stack up very well against the231's speed, mission capability andeconomy. True airspeeds of 180 to 190knots on a little more than 11 gallonsof fuel per hour are quite satisfying.The airplane is capable of climbing
30. APRIL1984STEEL DEALS MOONEY 231Mooney Aircraft faces an uncertain future.ability to produce parts for LTV products.Republic Steel, Mooney's owner for Mooney has increased its market11 years, seeks to merge with the Jones share of single-engine retractables from& Laughlin Steel Corporation, a subsidiary15.9 percent in 1981, to 19.5 percent inof the giant LTVCorporation. But in 1982, to 23.9 percent in 1983, when itmid-February, the U.S. Justice Departmentsold 154 aircraft. Last year would haveblocked the merger on antitrust been acceptable financially, Smith said,grounds, saying it would result in the except the company spent heavily oncreation of the nation's second largest development of the 301. With little helpsteel company, which would own a from Republic, which must contend withcommanding market in certain steel its own losses and concentrate on theproducts. At press time, Republic and LTV merger, Mooney has had to slowLTV were considering revising thedown work on the 301. Certification hadmerger plan to make it acceptable to theJustice Department.been targeted for early 1986; the revisedplan calls for late 1986 or early 1987.The proposed merger has spawned a Mooney still is marketing a militaryhost of rumors regarding Mooney's fate. trainer version of the 201/231, but noSome say that Republic, which has lost orders have been placed.$600 million in the last two years, is One group that has an emotional, ifready to sell its lone aircraft subsidiary. not vested interest in Mooney's fate isOthers claim LTV,which had a net loss the 2,500-member Mooney Aircraft Pi-.in 1983 of about $181 million on sales of lots Association (MAPA). An editorial in$4.6 billion, won't be bothered with little a recent issue of the MAPA's officialMooney if the merger goes through and publication raised the possibility of Mooneyowners buying the factory. "We'vesimply will shed the company. One finalbit of speculation: A competing aircraft had unofficial commitments from amanufacturer wants to buy Mooney and number of owners to participate in aput it out to pasture.purchase," MAPA President Mark HarrisThomas J. Smith, president of Mooney,discounts the speculation. Smith said hesaid. Harris said he was told by Republicthat Mooney is not for sale, but, just inhas seen no indication that Mooney case, he asked that MAPA be placed atwould be sold by either Republic or LTV, the top of the list of interested parties.and that it's "business as usual" in "If that's what it takes to keep theKerrville, Texas. However, Smith seems company going, we'd sure like to give itworried that LTVwon't find any value in the college try," Harris said. "Whohanging onto a small general aviation wouldn't like to own the company thataircraft manufacturer; he is promoting manufactures your aircraft?"the company as having the space and-Mark TwomblyPowerplantMooney M20K 231Base price $86,950Price as tested $177,370AOPA Pilot Operations/Equipment Category·;Cross country $110,740 to $119,870IFR$137,110 to $177,150SpecificationsTeledyne ContinentalTSIO-360LBIB210 hp @ 2,700 rpmRecommended TBO1,800 hrPropellerMcCauley, 2-bladeconstant-speed, 74 in diaLength25 ft 5 inHcigM8ft4~Wingspan36 ft 1 inWing area174.7 sq ftWing loading16.6 lb/sq ftPower loading13.8Ib/hpSea ts 4Cabin lengthCabin width9 ft 6 in3 ft 7.5 inCabin height3 ft 8.5 inEmpty weight1,800 lbEmpty weight, as tested2,051 lbMax weight (takeoff. landing) 2,9001bMax useful load 1,1001bUseful load, as tested849 lbPayload w/full fuel646 lbPayload w/full fuel, as tested395 IbFuel capacity, std 471.6 lb (453.6 lb usable)78.6 gal (75.6 gal usable)Oil capacity, ea engine8 qtBaggage capacity120 lb, 17 cu ftHat rack10 lb, 2.6 cu ftPerformanceTakeoff distance, ground roll 1,200 ftTakeoff distance over 50-ft obst 2,060 ftMax demonstrated crosswind component 12 ktRate of climb, sea level1,080 fpmMax level speed, sea level201 ktjr-
MOONEY 231 continuedvery quickly through weather. Onlyone mission was canceled due to reportsof moderate to severe icing conditions.And with the fuel tanks full,the 231 can cover long distances in asingle leg. At 65 percent power and24,000 feet, the airplane has a maximumendurance of six hours.Probably the biggest concern facingany potential Mooney customer is decidingwhether to buy a 201 or a 23l.Mooney suggests that, if your mission'requirements usually involve triplengths of less than 300 miles, the 201is your airplane. But, if you need totravel longer distances, the 231 is thebetter choice.And if Mooney and Continentalhave done their heat-managementhomework well-and our experiencewith N5737M indicates that they mayhave-you need not be concernedabout taking the 231 up high, where itbelongs. 0Cruise speed/Endurance (fuel consumption)@75% power, best economy8,000 ft167 ktj5.9 hr(66 pph/11 gph)22.000 ft188 kt/5.5 hr(66.6 pph/11.1 gph)@65% power, best economy12,000 ft161 kt/6.4 hr(59.4 pph/9.9 gph)24,000 ft179 kt/5.9 hr(60 pph/10 gph)@55% power, best economy12,000 ft150 kt/7.3 hr(49.8 pph/8.3 gph)24,000 ft163 kt/6.7 hr(52.8 pph/8.8 gph)Max operating altitude24,000 ftLanding distance over 50-ft obst 2,280 ftLanding distance, ground roll 1,080 ftLimiting and Recommended AirspeedsVx (Best angle of climb)71 KIASVy (Best rate of climb)96 KIASVa (Design maneuvering)118 KIASVfe (Max flap extended)112 KIASVie (Max gear extended)132 KIASVia (Max gear operating)ExtendRetractVno (Max structural cruising)Vne (Never exceed)Vr (Rotation)VSI(Stall clean)Vso (Stall in landing configuration)132 KIAS107 KIAS174 KIAS196 KIAS67 KIAS61 KIAS56 KIASAI(specifications are based on manufacturer'scalculations. All performance figures are basedon standard day, standard atmosphere, at sealevel and gross weight, u'liess otherwise noted.·Operations/Equipment Categories are definedin June 1983 Pilot, p. 96. The prices reflectthe costs for equipment recommended to operatein the listed categories.