MAULE MX-7-420 TURBO-PROP User manual

Rev. A
FOR
MAULE MX-7-420
TURBO-PROP

MAULE AEROSPACE TECHNOLOGY, INC.
MAINTENANCE MANUAL
FOR M-7-420A
Rev. A
i
FOREWORD
Ahead of you are many hours of flying pleasure. The more you fly your new M-7 the
more you will realize that flying this aircraft is a stimulating new sensation that will never grow
old.
The Maule M-7 is designed and built to give you the airplane you have always
wanted. It is fast, comfortable, and easy to fly, yet no light airplane is safer than the Maule
M-7. Its sturdy construction means you will not have to pamper it to enjoy long years of
trouble-free service.
Our dealers and distributors are anxious to serve you and will gladly furnish advice as
to proper servicing methods. You may also address requests for information on any items
not covered in this manual to Maule Parts-Service Department of Maule Air, Inc. (Telephone
912-985-2045, Ext. 239). In correspondence, please be certain to give complete information
on serial number, engine make and model, etc.
WARRANTY
Maule Air, Inc. warrants each new airplane manufactured by it to be free from defects
in material and workmanship under normal use and service, provided, however, that this war-
ranty is limited to making good at the Maule factory any part or parts thereof which shall,
within ninety (90) days after delivery of such airplane to the original purchaser, be returned to
Maule with transportation charges prepaid, and which upon Maule's examination shall dis-
close to its satisfaction to have been thus defective; this warranty being expressly in lieu of
all other warranties expressed or implied and all other obligations or liabilities on the part of
Maule, and Maule neither assumes nor authorizes any other person to assume for it any
other liability in connection with the sale of its airplane.
This warranty shall not apply to any airplane which shall have been repaired or al-
tered outside Maule's factory in any way so as, in Maule's judgment, to affect the airplane’s
stability or reliability, or which airplane has been subject to misuse, negligence or accident.
Certain items of equipment are warranted separately by their manufacturer. The en-
gine and accessories are warranted by Allison Gas Turbine Division, General Motors Corpo-
ration, Indianapolis, Indiana. The Hartzell Propeller is warranted by Hartzell Propeller, Inc.,
Piqua, OH. Avionics items are warranted by their manufacturers. Manufacturers of sepa-
rately warranted items of equipment request that warranty claims be made through your
nearest authorized Distributor or authorized Service Center. Maule Air will be glad to help
you find that facility nearest to you.

MAULE AEROSPACE TECHNOLOGY, INC.
MAINTENANCE MANUAL
FOR M-7-420A
Rev. A
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TABLE OF CONTENTS
ITEM PAGE
Foreword...................................................................….….. i
Warranty...............…................................................……… i
Table of Contents…............................…............................. ii
Log of Revisions…..................................……..................... iii
SECTION I - GENERAL DATA
General Description......................................……................ 1
Design Specification..........................................……........... 1
Fluid Capacities and Specification..........................……...... 2
SECTION II - GENERAL MAINTENANCE
Cleaning and Care of Aircraft.....……..........................….… 4
Inspection Guides............................……............................. 6
Rigging Procedures..............................……........................ 16
Lubrication.................................................…….......………. 18
Fabric Repairs…………………………………………………. 19
SECTION III - MAJOR COMPONENT PARTS
Wings.....................................................……...................… 20
Lift Struts.....................................................……..............… 20
Fuselage...........................................................…....…....… 20
Surfaces and Controls................................……………..….. 21
Landing Gear, Wheels and Brakes......……....................…. 22
Tailwheel………………………………………….…………….. 24
Figure One………………………………………….………….. 26
Power Plant System........…..............................……...…..… 27
Fuel System....................….............................……….….… 28
Electrical System................…...................................……… 29
Electrical Schematic………….......……………………….….. 32
Door Latch Adjustment Procedure....………..........……...… 35

MAULE AEROSPACE TECHNOLOGY, INC.
MAINTENANCE MANUAL
FOR MX-7-420
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LOG OF REVISIONS
Rev. To
Page(s) Description Date
A 3, 19,
23, 24 Added oleo strut oil API GL-4 or GL-5 85W-140 gear oil for new oleo spring P/N 4161B. 04/16/16

MAULE AEROSPACE TECHNOLOGY, INC.
MAINTENANCE MANUAL
FOR MX-7-420
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SECTION I
GENERAL DATA
GENERAL DESCRIPTION:
Type: Four/five place high wing cabin monoplane.
Engine Installation: Single tractor engine in nose of fuselage.
Wing: Strut braced, two spar, metal covered, modified USA 35-B airfoil. Fiberglass
wing tips.
Fuselage: Welded steel tube structure.
Fuselage and tail group covered with Ceconite synthetic fabric. Fiberglass
engine cowl. Aluminum skin on forward fuselage and doors.
Landing Gear: Main gear split axle type, spring-oil oleo shock absorber. Hydraulic
Brakes. Steerable tailwheel (Automatic locking).
Control Systems: Dual controls wheels, rudder pedals and brakes. All controls direct-
ly cable driven. Fuel control/shut off valve is at the left lower side
panel. Mechanical flap and trim controls are at the center on the
floor. All other controls, switches, etc., are instrument panel
mounted.
DESIGN SPECIFICATIONS:
Wing Span 30 feet 10 inches
Length 24 feet 5 inches
Height 6 feet 4 inches
Gross Weight 2500 lbs.
Empty Weight Approx. 1440 lbs.
Wing Loading 15.8 lbs./sq. ft.
Power Loading 6.8 lbs./BHP
Useful Load Approx. 1060 lbs.
Seats Four/five
Flaps Neg. 7°, 0°, 24°, 40°
Baggage Allowance 250 lb. Structural Limit
Baggage Compartment Dimensions 35 ½ H x 30W x 21L
Wings: a. Airfoil Modified USA 35-B
b. Chord 63 inches
c. Incidence +30 minutes
d. Dihedral 1.2 degrees
e. Sweepback None

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Areas:
a. Wing, Aileron and Flaps 157.9 sq.ft.
b. Ailerons (total) 12.6 sq.ft.
c. Flaps (total) 24.8 sq.ft.
d. Horizontal Stabilizer 18.1 sq. ft.
e. Elevators (including tab) 14.1 sq. ft.
f. Vertical Stabilizer 13.1 sq. ft.
g. Rudder 6.2 sq. ft.
h. Elevator Trim tab 1.03 sq. ft.
i. Rudder Tab .34 sq. ft.
FLUID CAPACITIES AND SPECIFICATIONS:
a. Main Fuel Tanks – (Jet A – wing leading edge inboard)
Right Main Tank 21.5 or 23.8 gallons
Left Main Tank 21.5 or 23.8 gallons
(Main fuel tanks considered one tank.)
b. Auxiliary Fuel Tanks – (Jet A – wing leading edge outboard)
Right Auxiliary Tank 15.0 gallons
Left Auxiliary Tank 15.0 gallons
c. Engine Oil (Mil-L-7808 and later and Mil-23699 and later) 10 quart max.
d. Brakes (Texaco Aircraft Hydraulic Oil 15, MIL-H-5606E or equiv.) 1 pint
e. Landing Gear - For P/N 4015B oleo spring, use New Holland No.134
hydraulic oil or Ford Tractor No. ESN-M2C134-D. 10W30 engine oil
may also be used. For P/N 4161B oleo spring use API GL-4 or GL-5
85W-140 gear oil
ENGINE FUEL SPECIFICATIONS
Primary MIL -T-5624L, grade JP-4 and JP-5
MIL-T-83133A, grade JP-8
ASTM D-1655, Jet B
ASTM D-1655, Jet A or A1
JP-1 fuel conforming to ASTM D-1655, Jet A
Arctic Diesel Fuel DF-A(VV-F-800B) conforming to ASTM D-1655, Jet A or A1
Diesel #1 fuel conforming to ASTM D-1655, Jet A
CAUTION Not all No. 1 diesel fuels or JP-1 fuels meet the primary fuel specifications. It is
the responsibility of the operator and supplier to determine whether a given fuel
meets these specifications.

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Emergency Mil-G-5572F, Aviation Gasoline, all grades (aircraft boost pump on; maximum
of 6 hours operation per overhaul period of turbine through an engine operat-
ing range of idle to 90% maximum SHP.)
CAUTION: MIL-G-5572 fuel containing tricresylphosphate (TCP) additive shall NOT be used.
Cold Weather To assure consistent starts below 4°C (40°F), the following fuels may be
necessary: MIL-T-5624, grade JP-4 ASTM D-1655, Jet B AVGAS/Jet A, Jet
A1, or JP-5 mixture (Refer to Cold Weather Fuels, para 2-48, of Allison 250-
B17 Engine Series Operation and Maintenance Manual for mixing/use of
cold weather fuel.)
NOTE Jet A, A1, JP-8 or JP-5 fuels are not restricted from use at ambient temperatures be-
low 0°F (-18°C); however, special provisions for starting must be made. (Refer to the Aircraft
Flight Manual.) Prolonged and uninterrupted operation with only AVGAS mixture will induce
lead buildup on turbine parts. This lead buildup can cause a gradual power reduction; con-
sequently, this AVGAS mixture should be used only for cold weather operation. During op-
eration with normal Jet A type fuel, the lead will slowly dissipate.
ENGINE OIL SPECIFICATION
The 250 Series engines are qualified and certified for use with MIL-L-7808 and subsequent,
and MIL-L-23699 series lubricating oils. The vendor brands of MIL-L-7808 and MIL-L-23699
series lubricating oils, which have been engine tested and accepted for use in the Model 250
engine, are listed in the Approved Oils paragraph of Allison 250-BI7 Engine Series Operation
& Maintenance Manual. Refer to para 1-73, Cold Weather Lubrication for the type of oil rec-
ommended at specific ambient temperatures.
NOTE Because of availability, reduced coking and better lubricating qualities at higher tem-
peratures, MIL-L-23699 oils are preferred for use in Model 250 engines. (Except for extreme-
ly cold weather operation, as indicated below).
Cold Weather Lubrication. The types of oil recommended at specific ambient temperatures
are as follows:
Ambient Temperature. Oil Type
0°C (32°F) and above MIL-L-23699, preferred
0°C (32°F) to -40°(-40°F) NM-L-23699 or MIL-L-7808G
-40°C (-40°F) and below MIL-L-7808G only
Approved Oils: Mixing of approved oils in 250 series engines is permitted only within a given
group number. An oil may be mixed with any other oil in its group. For example, an oil in
Group 23 may be mixed with another brand of oil in Group 23. Refer to the latest revision of
Allison 250-BI7 Engine Operations and Maintenance Manual (Publication 11W2) for ap-
proved oils, paragraph 1-74.
WARNING: Mixing of oils within an oil series but not in the same group is permitted only in
an emergency. Use of mixed oils (oils not in the same group) in an engine is limited to five

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hours total running time. Adequate maintenance records must be maintained to ensure that
the five-hour limit is not exceeded. Mixing of oils from different series is not permitted. Fail-
ure to comply with oil mixing restrictions can result in engine failure.
SECTION II
GENERAL MAINTENANCE
CLEANING AND CARE OF AIRCRAFT
Keeping the performance, speed and durability that was built into your aircraft at the
factory requires more than casual attention. The accumulation of dirt and oil on the outside
and debris inside does affect these factors and can be a fire hazard as well. The first step to
proper maintenance is a clean aircraft.
EXTERIOR
Frequent washing is good for your aircraft finish, especially during the first few
months. Use any quality car wash with a soft cloth or sponge and plenty of clean water-do
not use dishwashing detergent. Drying should be done with a chamois. Accumulation of oil,
grease and exhaust carbon deposits should be removed frequently by using a soft cloth
soaked in mineral spirits or other neutral cleaner.
For general polishing, apply a good quality car polish or wax according to instruc-
tions. Clean Plexiglas with plenty of soap and water using grit free soft cloth, chamois or
sponge. Use of a dry cloth on Plexiglas will not only cause scratches but will also build up an
electrostatic field which will attract dust to the surface. Blotting with a clean damp chamois
will remove the charge and the dust. After cleaning, polishing with a good Plexiglas cleaning
product such as "Mirror Glaze" will keep the glass clean and help polish out minor scratches.
Experience has shown that airplanes based at coastal airports or where there is an
otherwise corrosive atmosphere require special treatment to prevent corrosion, specifically
"electrolyte corrosion". Salt water and chemicals act as an electrolyte between dissimilar
metals and can start a strong corrosive action over a short period of time. Maule makes
every effort to separate dissimilar metals with primers and coatings during manufacture, but
there are some locations (such as rivets in wing skins) where this is impossible. To combat
corrosion it is important that the external painted surfaces be kept clean and well waxed.
Wash the airplane with fresh water frequently to remove any salt or chemical film. Periodi-
cally, coat the wings, flaps and ailerons internally with a quality corrosion preventative, sev-
eral of which are available. Floatplanes require more extensive preservation techniques
which are well known in the field.
INTERIOR
Floorboards should be vacuumed frequently and can be cleaned with any good rug
cleaner.

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Care should be taken in the disposal of candy wrappers, paper scraps, cigarette
butts, etc. These can work their way under the floorboards and become a fire hazard and
moisture trap.
NOTE: While washing the aircraft, ascertain that all drain holes are open. Clean out
any debris blocking them. Accumulated water can be dangerous, so check behind the bag-
gage compartment frequently.
Textile upholstery may be cleaned using a vacuum cleaner. Grease and oil spots on
the upholstery should be treated with a spot remover or dry cleaning fluid. Do not use soap
and water on textile materials.
Vinyl upholstery may be cleaned using soft whisk broom or suds of any mild soap
(castile or olive oil base) in lukewarm water. Use water sparingly as the upholstery otherwise
requires a long time to dry if water trickles through the seam stitches.
For best results, stains, especially those caused by grease or paint, should be re-
moved from upholstery as soon as possible or they may become “set”" and hard or impossi-
ble to remove. "Set" stains should be removed carefully with a clean cloth dampened in de-
natured alcohol. Stains caused by shoe polish can best be removed with turpentine. How-
ever, such cleaning agents are liable to affect the dust-repellent finish of the vinyl if used in
excess of the actual requirements. Never use volatile solvents such as lacquer thinner, ace-
tone, etc. on upholstery.
The cleaning should be completed by wiping the surface of the vinyl dry with a clean
cloth, particularly in the seam. No attempt should be made to apply preservatives such as
wax, polish, or varnishes, as these will not be absorbed by vinyl, but will merely collect dust.
There are protective treatments made especially for vinyl which are commercially available
and quite satisfactory.
Leather upholstery should be cleaned by leather cleaning methods using leather-
cleaning products.

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INSPECTION GUIDES
AIRFRAME INSPECTION
At 25 Hour Total Time, perform 50 Hour Inspection as described below:
At 50 Hour Total Time and every 50 hours thereafter:
1. Check battery for general condition and electrolyte level.
2. Check all main electrical connections.
3. Check fluid level in brake reservoirs.
4. Check the entire fuselage, tail surfaces and wing skins for cracks, security of fair-
ings and general condition.
CAUTION: If airplane is subject to excessive stress, i.e., heavy loads, adverse wind
conditions, rough landings, etc., take special care in examining wing skins for any
cracks. If any are found, repair before further flight in accordance with AC 43:13 and
factory drawings. (Do not replace any countersunk rivets with buttonhead rivets in wing
because it is not approved.)
5. Check aileron and flap skins for cracks.
6. Check the security, operation and general condition of all control surfaces.
7. Check main landing gear for condition and brakes for leakage and wear.
8. Check main landing gear oleo struts for oil leaks.
9. Check general condition of tailwheel, leaf springs and spring attachment. Leaf
springs should have 45°angle with no weight on the wheel. Check all bolts and
nuts holding the tail springs to the fuselage. Tighten nuts, if needed, so that there
is no play or side movement in the springs or their attachment.
10. Check tires for inflation and cuts.
11. Drain sumps of fuel tanks, checking for contamination and water.
At 100 Hours Total Time and every 100 Hours thereafter, perform the 50 hour inspection
plus the following:
1. Remove right and left kick panels in cockpit, windshield side post covers and panels
below seat fronts. Examine protective rudder cable guide tubes, (located behind
kick panels), if installed and attaching clamps, bolts and nuts for security and gen-
eral condition.