North American Aviation / Ryan / Navion / L-17

North American Aviation / Ryan / Navion / L-17

North American Aviation / Ryan / Navion / L-17

Construction Number Register — Reference Edition

⚠️ Living Document: This article is updated progressively. Data is sourced from verified aviation registers and will be expanded in multiple revision cycles. Treat as a reference module in the OAL S1000D-inspired documentation concept.

Aircraft Family Overview

Field Data
Full Type North American Navion
Sort Value Navion
Search Aliases Camair 480 · D-16 · L-17 · NA-145 · NA-154 · Navion · Riley · Twin Navion · U-18
C/n Known 2,478
C/n Range (Standard) NAV-4-xxxx
C/n Range (Twin Navion) TN-xx · TTN-xx · 1-xxx
Type Certificate TCDS A-782
TC Holder Sierra Hotel Aero, Inc. · South St. Paul, Minnesota
Era 1940s — vintage general aviation / liaison

Note: The standard production Navions have a construction number in the NAV-4-xxxx range. Twin Navion conversions have received a new construction number in TN-xx, TTN-xx or 1-xxx ranges.

Technical & Engineering Data

Technical and engineering data for the North American/Ryan Navion includes detailed aerodynamic reports, engine notes, stability studies, and performance sheets. Many historical documents, including the type certificate and service manuals, have been digitized and compiled by aviation organizations and enthusiast groups.

Aerodynamic & Stability Studies

Extensive flight mechanics data — including dynamic stability derivatives, flight-test extractions, and wind-tunnel estimates — has been well documented, largely thanks to studies sponsored by the FAA at institutions like Princeton University:

  • Stability Studies: NACA and FAA analyses (e.g., The Stability Derivatives of the Navion Aircraft Estimated by Various Methods) evaluate handling qualities and roll-yaw couplings. Access the full document via the Defense Technical Information Center (DTIC) ↗.
  • Handling Characteristics: The Navion's interconnected rudder-aileron control system provides exceptional spiral and directional stability. Further details on frequency-domain handling-quality evaluations are archived in the University of Tennessee TRACE Repository ↗.

Engine Technical Notes

The Navion is known for its rugged powerplant adaptability, evolving from initial military and early civilian configurations.

  • Original Powerplant: Most early models were equipped with the air-cooled, horizontally opposed 185-HP Continental E-185-3 engine (producing up to 205 HP at 2,600 RPM for short-term takeoff).
  • Upgrades: Later variants and aftermarket conversions regularly feature 260-HP or Continental IO-470/550 engines.
  • Continental Technical Data: Complete type design, engine limitations, and fuel/oil servicing specifications are outlined in the Department of Transportation Type Certificate Data Sheet.

Performance Data

The Navion's "fat wing" design and short-field capabilities are defining features of its performance.

Parameter Value
Cruising Speed Approximately 150–155 mph (130–135 knots)
Range 450 to 750+ nautical miles (depending on fuel tank configuration: 40 to 108+ gallons)
Rate of Climb ~900 to 1,250 feet per minute

Review a compiled sheet of basic weights, measurements, and speeds at the MAPS Air Museum Aircraft Specifications ↗.

Engineering Bulletins

Ryan and North American Aviation actively published field service bulletins and mandatory service instructions. Many have since been updated or superseded by FAA Airworthiness Directives (ADs). The complete official Service Bulletin registry is maintained by the TC Holder at navion.com/servicebulletins.html ↗.

AI Overview — Certification & Maintenance Quick Reference (Civil)

The North American / Ryan Navion is a vintage 1940s-era aircraft. Type Certificate (TC) A-782 is currently held by Sierra Hotel Aero, Inc. Navion maintenance is governed by Federal Aviation Regulations and detailed in original manuals, with community and parts support heavily centered around the American Navion Society and the TC Holder.

1. Essential Certification Documents

Document Description
TCDS A-782 Core FAA document defining approved limits, eligible engines, and required equipment. View Navion TCDS ↗
Maintenance & Service Manuals Originally published by North American Aviation and Ryan Aeronautical — standard maintenance practices, inspections, and system operation
FAA Form 337 Required for any major repair or alteration beyond standard maintenance — commonly used for engine upgrades (Continental / Lycoming) and airframe modifications
Airworthiness Directives (ADs) Legally mandated inspections covering airframe parts, landing gear systems, and control surfaces. Check the FAA Dynamic Regulatory System ↗

2. Standard Maintenance Procedures

  • Annual & 100-Hour Inspections: Follow standard 14 CFR Part 43 procedures with heavy focus on recurring ADs — particularly landing gear retraction mechanism and wing spar integrity.
  • System Familiarity: The Navion relies extensively on ex-military parts (often Delco-Remy electrical) and mechanical systems. Maintenance personnel must be familiar with its unique stress-skin wing design (built without a primary spar) and pressure carburetor fuel systems.
  • Specialized Support: Referencing vintage manuals and consulting veteran Navion mechanics — often found through the TC holder or the type club — is standard operating procedure for troubleshooting.

3. Resources & Parts

Resource Details
TC Holder Sierra Hotel Aero, Inc. · South St. Paul, Minnesota · navion.com ↗
Owner's Organization American Navion Society ↗ — forum, conventions, approved maintenance documentation, Form 337 cache

L-17 Military Variant — Maintenance Reference

Maintaining a Navion L-17 liaison aircraft requires strict adherence to historical U.S. military Technical Orders and original service manuals. Routine upkeep focuses on its hydraulic landing gear, electrical systems, and the Continental E-series engines, often requiring specialized knowledge from vintage aircraft mechanics.

Core Maintenance Areas

System Key Points
Hydraulic System Controls landing gear, flaps, and cowl flaps. Brake and gear line bleeding requires careful pressure application. Routine filter changes: NAPA Gold 1071/1080 · AC Delco PF-316 · FRAM C-134PL.
Engine Continental E-185 or E-205 depending on sub-variant. Run "on condition" — strict AD compliance for magneto and propeller mandatory.
Electrical System 25- or 35-amp generators. Check every 10–50 flight hours. Battery fluid levels require increased frequency in warm climates.
Inspections Annual condition inspections by A&P mechanic with Inspection Authorization (IA). Ideally familiar with vintage post-war aircraft.

Essential Military Documentation (Technical Orders)

Document Scope
T.O. 1L-17A-2 Erection & Maintenance Manual — assembly, rigging, system troubleshooting
T.O. 1L-17A-4 Parts Catalog — superseded and exact-match hardware identification
T.O. 01-100LAA-6 Inspection Requirements — 50-hour, 100-hour, and annual inspection checklists

L-17 Specialist Resources & Community

Resource Details
Navioneers Community Preserves L-17 history and provides technical documentation and library access for operators
L-17.org Registry l-17.org ↗ — dedicated L-17 registry and documentation archive
Classic Aero Service Aurora, Nebraska — specialist Navion maintenance shop
Regional Specialists Navion-specialist mechanics based in Massachusetts and Virginia

Service Bulletins & Mandatory Service Letters

The complete official Service Bulletin registry is maintained by the TC Holder at navion.com/servicebulletins.html ↗. The register spans three issuing authorities: North American Aviation (1946–1948), Ryan Aeronautical / Ryan-NAI (1946–1970), and Sierra Hotel Aero (2004–present).

▶ North American Aviation Service Bulletins (1947–1948)
SB No. Subject Date
No. 18 Generator Terminal Insulator Installation Feb. 14, 1947
No. 20 Hartzell No. 8628 Prop Blade Tip Rework Jan. 28, 1947
No. 23 Carburetor Vapor Return Line Hose April 11, 1947
No. 26 Controlled Hydraulic Power Sys Install April 01, 1947
No. 30 Hartzell Propeller Piston Guide Pin May 05, 1947
No. 31 Engine Mount Front Frame Reinforcement May 09, 1947
No. 32 Fuel Strainer Drain Cock Replacement May 01, 1947
No. 33 Elevator Leading Edge Rib Installation July 02, 1947
No. 36 Fuel Pump Inlet Lines Relocation March 15, 1948
▶ Ryan Aeronautical Service Bulletins (1949–1955)
SB No. Subject Date
No. 04 Inspect Nose Gear Retract Drag Link Aug. 05, 1949
No. 05 Propeller Counterweights Jan. 03, 1949
No. 08 End Fitting — Hyd Power and Control July 11, 1949
No. 09 Inspect Shakespeare Throttle Control Sept. 01, 1950
No. 12 Improved Cabin Seating Feb. 01, 1951
No. 16 Carburetor Air Duct Change Feb. 12, 1952
No. 18 Aileron Control Chain Jamming Sept. 26, 1952
No. 19 Inspection, Stabilizer Front Attach Ftg Feb. 16, 1953
No. 21 Relative Motion Between Fuselage/Wings Aug. 05, 1954
No. 22 Cracks in Fuselage Frame STA 294.1 Nov. 16, 1954
No. 23 Inspect Rear Wing Spar Junction Ftg Dec. 05, 1955
▶ North American Aviation Full SB Series (1946–1948) — NA-145 / NA-154
SB No. Subject Date
No. 01 Temporary Removal of Hyd Pwr System Oct. 08, 1946
No. 02 Fuel Filler Drain Installation Dec. 06, 1946
No. 03 Separate Hyd Relief Valve Installation Oct. 21, 1946
No. 04 Landing Gear Up-Lock Control Rework Oct. 29, 1946
No. 05 Propeller Control Replacement Nov. 01, 1946
No. 06 Crankcase Breather Line Rework Nov. 14, 1946
No. 07 Fuel Accumulator Tank Sump Fitting Nov. 19, 1946
No. 08 PS-5C Carburetor Identification Nov. 27, 1946
No. 09 Exhaust Tail Pipe Weld Rework Nov. 19, 1946
No. 10 Baggage Compartment Placard Dec. 06, 1946
No. 11 Valve Spring Spacer Installation Feb. 04, 1947
No. 12 Nose Wheel Valve Stem Clearance Nov. 27, 1946
No. 13 Push Rod and Valve Rocker Modification Feb. 04, 1947
No. 14 Landing Gear Control Handle Lock Jan. 02, 1947
No. 16 Oil Cooler Baffle Installation Jan. 06, 1947
No. 17 Carb Air Straightener Installation Jan. 16, 1947
No. 18 General Terminal Insulator Installation Feb. 14, 1947
No. 19 Nose Gear Actuating Cylinder Replace Jan. 23, 1947
No. 20 Hartzell No. 8628 Prop Blade Tip Rework Jan. 28, 1947
No. 21 Nose Gear Steering Bellcrank Replace Jan. 23, 1947
No. 22 Brake Assembly Rework Feb. 06, 1947
No. 23 Carburetor Vapor Return Line Hose April 11, 1947
No. 24 Temp Removal of Eng-Driven Hyd Pump March 04, 1947
No. 25 Starter Engagement Mechanism Rework May 12, 1947
No. 26 Controlled Hyd Pwr System Installation April 01, 1947
No. 27 Starter Pedal Reinforcement Bracket March 26, 1946
No. 28 Nose Gear Hyd Cylinder Line Replace April 03, 1947
No. 29 Delco Remy Starting Motor Modification April 15, 1947
No. 30 Hartzell Prop Piston Guide Pin Safety May 05, 1947
No. 31 Engine Mount Front Frame Reinforce May 09, 1947
No. 32 Fuel Strainer Drain Cock Replacement May 01, 1947
No. 33 Elevator Leading Edge Rib Installation July 02, 1947
No. 35 Cabin Heater Fuel Control Valve Inspect June 17, 1947
No. 36 Fuel Pump Inlet Lines Relocation March 15, 1948
▶ Ryan/NAI Service Bulletins (1948–1970)
SB No. Subject Date
No. 01 Nose Gear Inner Cyl Bearing Retainer Jan. 01, 1947
No. 02 Nose Gear Extension Restrictor March 22, 1948
No. 03 Nose Gear Drag Brace Attaching Struc May 20, 1948
No. 04 Insp Nose Gear Retract Drag Link Aug. 05, 1949
No. 05 Propeller/Counterweights Jan. 03, 1949
No. 06 Insp of Main Landing Gear Housing Jan. 18, 1949
No. 07 Navion Fuel System Feb. 15, 1949
No. 08 End Fitting — Hyd Pwr and Ctrl Unit Shaft July 11, 1949
No. 09 Inspect Shakespeare Throttle Control Sept. 01, 1950
No. 10 Hartzell Prop Control Unit Dec. 29, 1950
No. 11 Insp Throttle Act Lnd Gear Horn Switch Feb. 01, 1951
No. 12 Improved Cabin Seating April 15, 1951
No. 13 Land Gear Retract Link Inspection April 15, 1951
No. 14 Baggage Compartment Fuel Tank May 01, 1951
No. 15 Carb Air Induction Sys July 02, 1951
No. 16 Carb Air Duct Change Feb. 12, 1952
No. 17 Cracking of Stab Fwd Attach Fittings Sept. 26, 1952
No. 18 Aileron Control Chain Jamming Sept. 26, 1952
No. 19 Inspect Stab Front Attach Fittings Feb. 16, 1953
No. 20 Increased Eng Cowl Flap Opening March 27, 1953
No. 21 Relative Motion Between Fuse & Wing August 05, 1954
No. 22 Cracks in Fuselage Frame Sta 294.1 Nov. 15, 1954
No. 23 Insp Rear Wing Junction Fittings Dec. 05, 1955
No. 24 Insp Forward Eng Mounts Dec. 05, 1955
No. 25 Insp Nose Gear Drag Links Dec. 05, 1955
No. 33 Repair Cracked Elevator Leading Edges Nov. 01, 1947
No. 34 Landing Gear Retract Link Insp Dec. 17, 1958
No. 37 Missing Rivets in the Rudder Beam Assy June 26, 1970
No. 66 Instrument Panel Support Nov. 21, 1966
No. 101 Fuel System — Fuel Selector Valve June 24, 2004
No. 102 Airframe Engine Mount July 13, 2004
No. 103 Airframe Fuselage Reinforcing Kit July 20, 2004
▶ Sierra Hotel Aero Service Bulletins (2004–present)
SB No. Subject Date
No. 101A Fuel System — Fuel Selector Valve Aug. 23, 2005
No. 102A Airframe — Engine Mount July 13, 2004
No. 103A Airframe — Fuselage Reinforcing Kit July 17, 2009
No. 106A Fuel System Inspection May 01, 2007
No. 107 Auxiliary Fuel System Placarding June 08, 2012
No. 108R1 Cabin Air Valve Housing Support Nov. 19, 2013
No. 109 Frame Assembly Station 311.07 Inspection Sept. 16, 2013
▶ Mandatory Service Letters
SL No. Subject Date Issued By
No. 78 Fuel Accumulator Tank — Replacement — Navion
No. 81 P/N 145-58145-3 End Fitting Hyd Pwr/Ctrl March 31, 1961 Navion
No. 85 Loose Rivets — Wing Skin/Stringer January 07, 1964 Navion
No. 87 Fuel Accumulator Tank — Replacement February 20, 1965 Navion
No. 88 Wing Closure Strip — Inspection February 20, 1965 Navion
No. 90 Usage of 6.50-8 6-Ply Main Landing Gear Tire June 14, 2023 Sierra Hotel Aero

Construction Number Register — External Reference

The full construction number rundown (2,478 c/n known) is maintained and searchable via the Spottingmode database:

🔗 North American Navion — Full C/n Rundown (Spottingmode)

  • Standard production Navions — c/n range NAV-4-xxxx
  • Early prototypes — c/n range 143-x
  • Twin Navion conversions — c/n ranges TN-xx · TTN-xx · 1-xxx
  • Military variants: L-17A/B/C · D-16 · U-18
  • Derivative types: Camair 480 · Riley Twin Navion

Revision Log

Annual Inspection Checklist — A to Z Procedures

⚠️ Reference Use Only. Derived from the American Navion Society Annual Inspection framework. All maintenance must be performed by a licensed A&P mechanic with IA in accordance with 14 CFR Part 43 and applicable ADs.

Format: Item · Chk · Rmrks · Description

▶ Step 1 — Preparation
Item Chk Rmrks Description
1.01 ____ ____ Review American Navion Society Video Maintenance Seminar Series One "The Annual."
1.02 ____ ____ Review AD's and Type Certificate equipment lists.
1.03 ____ ____ Review Navion Service Manual and Parts Manual.
▶ Step 2 — Pre-Inspection Flight
Item Chk Rmrks Description
2.01 ____ ____ Handling on the ground.
2.02 ____ ____ All instruments working.
2.03 ____ ____ Engine producing full power on takeoff.
2.04 ____ ____ Gear and flap retraction and hydraulic pressure.
2.05 ____ ____ Smooth operation of engine and flight controls.
2.06 ____ ____ Aircraft rigging in flight.
2.07 ____ ____ Landing gear warning horn.
2.08 ____ ____ Brakes.
2.09 ____ ____ Canopy operation.
2.10 ____ ____ Inspection of log books, airworthiness and registration certificates, radio station license and AD note compliance.
2.11 ____ ____ Verify weight and balance calculations.
▶ Step 3 — Owner's Squawk List
Item Chk Rmrks Description
3.01 ____ ____ Short conversation with owner on items of concern: oil/hydraulic leaks, tires, batteries, ELT, antennas, etc.
3.02 ____ ____ List work to be performed per item 3.01.
▶ Step 4 — Main and Nose Landing Gear
Item Chk Rmrks Description
4.01 ____ ____ Remove all inspection plates. Make sure proper ANS screws are used on landing gear access plate #14514222.
4.02 ____ ____ Check for corrosion, worn parts, freedom of all 3 uplock rollers and condition of bumper washers on mains.
4.03 ____ ____ Place airplane on jacks.
4.04 ____ ____ Remove main wheels; clean and pack bearings; grease gear; inspect brakes; check tire inflation; inspect hydraulic cylinders; inspect wheels for cracks.
4.05 ____ ____ Retract gear; inspect for clearance and locking position.
4.06 ____ ____ Check scissor bolts and bushing for wear.
4.07 ____ ____ Inspect struts for looseness, fluid leaks and cracks in weld at trunnion junction.
4.08 ____ ____ Check seating mechanism for worn bushing and bolts.
4.09 ____ ____ Check for side movement of trunnion bearing; add washers as necessary.
4.10 ____ ____ Remove nose wheel and pack bearing; inspect wheels for cracks; check inflation air pressure.
4.11 ____ ____ Check nose gear collar assembly to fork bolts (4) for torque.
4.12 ____ ____ Check wiper ring retainer nut P/N 145-34135; tighten clockwise with spanner wrench. Do not over-tighten.
4.13 ____ ____ Check nose gear doors for proper closing; replace wheel; retract and check clearance.
4.14 ____ ____ With nose gear retracted, visually inspect full locking clearance and centering in wheel well.
4.15 ____ ____ Check actuating cylinder for full travel (need 1/16" before bottoming).
4.16 ____ ____ Inspect nose gear hydraulic cylinder for leakage, tightness and hose chafing.
4.17 ____ ____ Check nose gear drag brace support bungee spring for straightness. If curvature noted, replace bungee assembly.
4.18 ____ ____ Inspect gear retract hat section P/N 145-34161 for cracks around forward end, top and bottom.
4.19 ____ ____ Check hydraulic retract cylinder mounting brackets for loose rivets.
▶ Step 5 — Fuel System
Item Chk Rmrks Description
5.01 ____ ____ Visually check all tank fuel lines for stains and leaks (mains, aux and accumulator).
5.02 ____ ____ Flush main fuel screen and replace safety wires.
5.03 ____ ____ Remove and clean gascolator screen and bowl in nose gear well.
5.04 ____ ____ Remove screen on fuel injection system control valve; turn on boost pump to flush.
5.05 ____ ____ Remove and clean fuel screen in carburetor.
5.06 ____ ____ Check fuel selector valve for leaks, cleanliness, ease of operation and proper placard.
5.07 ____ ____ Check baggage compartment, underseat, and wingtip auxiliary tanks and valves (if installed).
5.08 ____ ____ Check fuel gauge sending units (in tanks) for leaks or stains.
5.09 ____ ____ Verify operation of fuel gauges.
5.10 ____ ____ Check fuel tank vents.
▶ Step 6 — Wings
Item Chk Rmrks Description
6.01 ____ ____ Skin: Check for loose rivets and corrosion.
6.02 ____ ____ Inspect wings with flaps extended. Inside surfaces free of dirt, debris and corrosion. Check hydraulic lines.
6.03 ____ ____ Check control mechanisms for cotter pins. Check aileron balance weights.
6.04 ____ ____ Ailerons and flaps: Check control cables for condition, correct routing and tension.
6.05 ____ ____ Check bolts and bushings for wear.
6.06 ____ ____ Check condition of electrical wiring.
6.07 ____ ____ Check rigging of ailerons and flaps and that aileron trim tab is not bent to extreme angle.
▶ Step 7 — Fuselage and Cabin
Item Chk Rmrks Description
7.01 ____ ____ Check for corrosion of aft section of cabin, especially in floor area.
7.02 ____ ____ Remove baggage curtain; check fuselage aft section for dirt, plugged drain holes, corrosion. Check wiring and avionics in aft fuselage.
7.03 ____ ____ Clean and check trim tab mechanism.
7.04 ____ ____ Check bulkhead No. 294-10 for cracks if "Texas-Patch" is not installed.
7.05 ____ ____ Remove front seats for visual inspection under panel. Check for hydraulic and oil leaks, freedom of control column, loose wires and hoses.
7.06 ____ ____ Check condition of safety belts.
7.07 ____ ____ Clean seat rails and lube for ease of movement; check locking mechanism.
7.08 ____ ____ Check engine controls for ease of movement and placards.
7.09 ____ ____ Check all instruments, gauges and switches for proper placarding.
7.10 ____ ____ Check magnetic compass for fluid and compass card. Operate radios and instrument lights; observe compass reactions.
7.11 ____ ____ Check window glass for cracks and discoloration.
7.12 ____ ____ Wash down airplane and clean as required.
7.13 ____ ____ Check condition of pitot tube and static ports.
7.14 ____ ____ Slide canopy back and forth. Check ease of operation, security of latching, corrosion, wires, windows, placard and emergency opening mechanism.
7.15 ____ ____ Check heater for ease of operation of controls and functioning of blower.
7.16 ____ ____ Check cabin air intake and exhaust controls for operation. Make sure vents are clear of debris.
7.17 ____ ____ Check all external fairings to ensure security.
▶ Step 8 — Empennage
Item Chk Rmrks Description
8.01 ____ ____ Check skin for corrosion and loose rivets.
8.02 ____ ____ Check freedom of movement of flight controls.
8.03 ____ ____ Lube pulleys and check bolts for cotter pins and safety wires.
8.04 ____ ____ Check trim tabs for proper alignment.
8.05 ____ ____ Make sure vertical fin top fairing and fuselage fairings are secure and without cracks.
▶ Step 9 — Electrical System and Avionics
Item Chk Rmrks Description
9.01 ____ ____ Remove battery from box; clean and paint box as necessary. Inspect wiring around master solenoid (relay).
9.02 ____ ____ Clean battery. Check water level and log specific gravity: __________________
9.03 ____ ____ Check fuses and circuit breakers for placarding and amperage designations. Inspect behind panel for unauthorized in-line fuses.
9.04 ____ ____ Pitot heat: Verify operation (if installed).
9.05 ____ ____ Check operation of wingtip and tail position lights. Inspect sockets, bulbs and lenses for security and absence of corrosion.
9.06 ____ ____ Check operation of landing lights and physical security to struts. Inspect for corrosion, wiring and condition of lenses.
9.07 ____ ____ During landing gear retract test, observe operation of landing gear lights and gear warning horn.
9.08 ____ ____ Check operation of panel / instrument / avionics lights and dimmer.
9.09 ____ ____ Check cabin (canopy dome) light.
9.10 ____ ____ Verify that required spare fuses and lamps are on board.
9.11 ____ ____ During engine tests, verify ammeter readings and alternator or generator operation.
9.12 ____ ____ Check operation of headset jacks and cabin loudspeaker with engine off and running to detect audio noise (e.g. alternator whine).
9.13 ____ ____ Verify operation of hand/boom/headset microphones, PTT keying control, speaker muting-relay and/or intercom if installed.
9.14 ____ ____ Check operation of NAVCOMs, ADF, transponder, DME, autopilot and any other avionics. Verify radio operation by radio-check call to ATC facility.
9.15 ____ ____ Inspect all antennas for security, cleanliness, condition of elements and connectors.
9.16 ____ ____ Observe anti-collision (beacon) and strobe lights for proper operation; check for radio noise introduction.
9.17 ____ ____ Check physical mounting of avionics.
9.18 ____ ____ Check operation of cooling fan (if installed) or make sure avionics vents are clear.
▶ Step 10 — Hydraulic System
Item Chk Rmrks Description
10.01 ____ ____ Check hydraulic reservoir for filter condition and fluid level.
10.02 ____ ____ Check lines and hoses for condition, routing and leaks.
10.03 ____ ____ Actuating cylinders (left and right main gear): Check for cracks. Also shaft P/N 143-33153 for cracks in cotter pin hole.
10.04 ____ ____ Remove 1/4 bolt to actuating cylinder to check travel. Needs 1/16" before bottom.
10.05 ____ ____ Check for down pressure. Remove lower hose on hydraulic cylinder in nose gear well; install hydraulic pressure gauge. Pump auxiliary (hand) hydraulic pump; observe pressure.
10.06 ____ ____ Check master control valve under panel for O-ring leaks and line security.
10.07 ____ ____ Hydraulic pressure must be 1,125 psi ± 25 psi.
▶ Step 11 — Brakes
Item Chk Rmrks Description
11.01 ____ ____ Inspect brake drums for wear.
11.02 ____ ____ Check brake blocks for glazing; if glazed, roughen with emery cloth.
11.03 ____ ____ If hand pump or pedals need to be pumped to obtain pressure, replace blocks or pucks.
11.04 ____ ____ It may be necessary to bleed brakes to obtain a firm pedal.
11.05 ____ ____ Brake adjustment valves are installed in most Navions. Adjust if taxi tests indicate need.
▶ Step 12 — Engine
Item Chk Rmrks Description
12.01 ____ ____ Drain oil and change filter or oil screen. Recommendation: change oil and filter and perform oil analysis by laboratory.
12.02 ____ ____ Remove plugs and clean, gap, test.
12.03 ____ ____ Run compression test and log results. Cylinder #: 1 ___ 2 ___ 3 ___ 4 ___ 5 ___ 6 ___
12.04 ____ ____ Check timing.
12.05 ____ ____ Check routing and condition of all hoses in engine compartment.
12.06 ____ ____ Check exhaust system for cracks and leaks.
12.07 ____ ____ Remove heater muff for inspection. Check for leaks, corrosion, cracks, carbon.
12.08 ____ ____ Clean air filter and check alternate air, if appropriate.
12.09 ____ ____ Inspect intake pipes, hoses and clamps.
12.10 ____ ____ Check baffles and seals for condition.
12.11 ____ ____ Inspect engine controls for ease of movement.
12.12 ____ ____ Check engine mounts.
12.13 ____ ____ Check cowling and hoods for cracks and loose rivets. Also check hood and cowling moldings.
12.14 ____ ____ Inspect engine for oil leaks.
12.15 ____ ____ Check crankcase for cracks.
12.16 ____ ____ Check cowl flaps for operation and security.
12.17 ____ ____ Run engine check for idle RPM and mag drop.
12.18 ____ ____ Check all engine compartment wiring for security, cracks in insulation, routing and termination.
12.19 ____ ____ Wash down and/or clean engine and engine compartment.
12.20 ____ ____ Check security and condition of all engine accessories.
▶ Step 13 — Propeller
Item Chk Rmrks Description
13.01 ____ ____ Remove spinner and check for cracks and loose rivets.
13.02 ____ ____ Check prop for oil leaks and loose blades.
13.03 ____ ____ Inspect blades for nicks and damage.
13.04 ____ ____ Inspect hub for corrosion and security.
13.05 ____ ____ Repair minor nicks on leading edge of blades.
13.06 ____ ____ Clean and spray flat black on back of prop if needed.
13.07 ____ ____ Inspect governor for oil leaks and security.
13.08 ____ ____ Note: Any major repairs must be performed by an approved propeller repair station.
▶ Step 14 — Miscellaneous
Item Chk Rmrks Description
14.01 ____ ____ Make up list of applicable AD's. Check and log compliance.
▶ Step 15 — Logbooks and Maintenance Check Flight
Item Chk Rmrks Description
15.01A ____ ____ Enter inspection work in the Airplane Logbook.
15.01B ____ ____ Enter inspection work in the Engine Logbook.
15.01C ____ ____ Enter inspection work in the Propeller Logbook.
15.02 ____ ____ Have owner/pilot preflight and fly airplane; perform maintenance check flight and enter in log.
Revision Date Scope Rev. 1 May 2026 First release — Aircraft family overview · Civil certification quick reference · L-17 military maintenance reference · Full Service Bulletin registry · Mandatory Service Letters · C/n register link Rev. 2 TBD Technical & engineering data expansion · OAL document links · Additional c/n data

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