AC 121-1A

Change 4Historical

Advisory circular · Standard Operations Specifications - Aircraft Maintenance Handbook

Approved
July 7, 1978
Last reviewed
October 25, 2024
Cancels
AC121-1A CHG 3AC120-21AC120-24A
Family
AC 121-1 · 1 version
Revision
A, change 4
14 CFR parts
1

Guidance, not mandatory unless a rule or AD requires it. DRS record last changed November 22, 2025.

Show pages 286–297
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Cyl) Portable *OC X X *(4 Yrs. Hyd Check or cyl.

replacement appropriate to Cyl) Masks OC X X Pressure Gage OC X X Pressure Regulator OC X X Effective date ____________________ Page 6 of 7

OPERATIONS SPECIFICATIONS

AIRCRAFT MAINTENANCE HAWKER-SIDDELEY DH-125 SERIES

OVERHAUL INSPECTION AND CHECK PERIOD LNDGS., HOURS OR YRS PF PI OTHER Oxygen, Chapter 35 (Cont'd) Valves:

Flow Selector OC X Charging OC X Supply Master OC X Airborne Auxiliary Power, Chapter 49 OC X X Aux. Power Unit 1,000 APU Hrs. X X Fuel Filter 2,000 APU Hrs. X X Generator OC X Ignitor Unit 1,000 APU Hrs. X X Solenoid Fuel Valve 6,000 APU Hrs. X X Valve Fuel Check 4 Yrs. X Doors, Chapter 52 OC X X Cargo OC X X Emergency Exits OC X Passenger OC X X Fuselage, Chapter 53 OC X X Nacelle/Pylons, Chapter 54 OC X X Airframe Engine Mount Brackets 10,000 X Stabilizers,

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Chapter 55 OC X X Elevator and Rudder Hinge Fittings OC X Horizontal Stabilizer Attach Points OC X Vertical Stabilizer Attach Points OC X Wings, Chapter 57 OC X X Internal Structure OC X Engine, Chapter 72 OC X X Engine, Bristol Siddeley Viper 1,600 X X Engine, Mount OC X EC Detail Insp.

Engine, Cowling OC X X Fire, Seal OC X EC Detail Insp.

Tail Cone OC X EC Detail Insp.

Effective date ____________________ Page 7 of 7

OPERATIONS SPECIFICATIONS

AIRCRAFT MAINTENANCE HAWKER-SIDDELEY DH-125 SERIES

OVERHAUL INSPECTION AND CHECK PERIOD LNDGS., HOURS OR YRS PF PI OTHER Engine Fuel System, Chapter 73 OC X X Air/Fuel Ratio Control EO X Barometric Flow Control EO X X Electric Pressure Control EO X X Flowmeter Transmitter EO X X Fuel Filter EO X Fuel Pump EO X Pressure Switches EO X Primer Solenoid EO X Pressure Increasing Valve EO X Rate Reset Valve EO X

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Engine Ignition, Chapter 74 OC X X Igniter Plug 375 X Exciter System EO X Glow Plugs OC X Engine Bleed Air, Chapter 75 OC X X Anti-Ice Valve EO X Engine Controls, Chapter 76 OC X X Power Control Linkage OC X X EC Detail Insp.

H.P. Fuel Cock Linkage OC X X Engine Indicating, Chapter 77 OC X X Tach. Generator EO X EGT Probes EO X X Power Loss Indicator EO X Oil System, Chapter 79 OC X X Pressure Indicator 3,000 X Pressure Transmitter OC X C at EO Tank OC X EC Detail Insp.

Temperature Indic. 3,000 X Temperature Bulb OC X C at EO Effective date ____________________ ---------------------------------------------------------------- ---------------------------------------------------------------- FIGURE 37. OPERATIONS SPECIFICATIONS

- AIRCRAFT MAINTENANCE - HFB 320 HANSA JET Form Approved UNITED STATES OF AMERICA Budget Bureau FEDERAL AVIATION AGENCY No 04-R075

WASHINGTON

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PART D Page 1 of 15

OPERATIONS SPECIFICATIONS

AIRCRAFT MAINTENANCE - GENERAL HFB 320 HANSA JET Thorough inspection shall be accomplished in accordance with the applicable procedures as listed in ABC Airlines Maintenance Manual.

Preflight shall be accomplished each service calendar day.

Inspection shall be in accordance with the applicable procedures listed in ABC Airlines Maintenance Manual.

Special Inspections The frequency and procedure for performing special inspections will be accomplished as specified in the operator's maintenance manual.

Overhaul and inspection/check period time limitations specified in hours and calendar time are maximum limits of whichever occurs first.

Period Inspections (PI) Period inspections will be accomplished as specified in ABC Airlines Maintenance Manual.

Aircraft shall not be utilized in air carrier or commercial operations unless:

a. The aircraft and its component parts, accessories, and appliances are maintained in an airworthy condition in accordance with the schedule of maintenance and inspection functions and procedures set forth in the operator's maintenance manual.

b. OC "On Condition" items are maintained in continuous airworthiness condition by periodic and progressive inspections, checks, services, repairs, and/or preventive maintenance and shall be appropriately described in the operator's maintenance manual.

c. Parts or subcomponents not listed below are checked, inspected and/or overhauled at the same time limits specified for the component or accessory to which such parts or subcomponents are related.

d. FC/BC items are done in accordance with manufacturer's recommendations.

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Effective date ____________________ Page 2 of 15

OPERATIONS SPECIFICATIONS

AIRCRAFT MAINTENANCE GENERAL HFB 320 HANSA JET The following PERIOD INSPECTIONS will be accomplished in accordance with instructions contained in ABC Airlines Maintenance Manual.

1. POST FLIGHT INSPECTION To be accomplished not to exceed 25 hours time in service as indicated by "X" under PO column on the following pages.

2. MID PERIOD INSPECTION To be accomplished at intervals not to exceed 60 hours time in service, as indicated by "X" under MP (PI) column on the following pages.

3. A PERIOD INSPECTION To be accomplished at intervals not to exceed 150 hours time in service, as indicated by "X" under A (PI) column on the following pages.

4. B PERIOD INSPECTION To be accomplished at intervals not to exceed 300 hours time in service, as indicated by "X" under B (PI) column on the following pages.

5. C PERIOD INSPECTION To be accomplished at intervals not to exceed 600 hours time in service, as indicated by "X" under C (PI) column on the following pages.

6. D PERIOD INSPECTION To be accomplished at intervals not to exceed 1200 hours time in service, as indicated by "X" under D (PI) column on the following pages.

7. E PERIOD INSPECTION

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To be accomplished at intervals not to exceed 2400 hours time in service, as indicated by "X" under E (PI) column on the following pages.

Effective date ____________________ Page 3 of 15

OPERATIONS SPECIFICATIONS

AIRCRAFT MAINTENANCE GENERAL HFB 320 HANSA JET Abbreviations used in the HFB 320 Hansa Jet maintenance schedule are defined as follows:

PO - Indicates Post Flight Inspection MP - Indicates Mid Period Inspection PI - Indicates Period Inspections HS - Indicates Engine Hot Section Inspection EC - Indicates Engine Change Inspection EO - Indicates Engine Overhaul OC - Indicates On Condition HYD - Indicates Hydrostatic Test CALIB -Indicates Calibration FC - Functional Check BC - Bench Check Life Limited Components:

1. Main Landing Gear P/N 320-50125/50150 15,000 hours

2. Nose Landing Gear P/N 320-50165 15,000 hours

3. Flap Assembly P/N 320-11700/12700 17,500 hours

4. Frame 28 (Aircraft Serial No. 1023) 10,000 hours The times quoted above are predicated on one landing per hour.

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Effective date ____________________ Page 4 of 15

OPERATIONS SPECIFICATIONS

AIRCRAFT MAINTENANCE HFB 320 HANSA JET

OVERHAUL PERIOD INSPECTIONS HOURS OR YRS. PO MP A B C D E Air-Conditioning System, Chapter 21 OC X X X X X X X Check Valves, APU, Air Conditioning OC X X X X X Air Flow Regulator 4,000 X X X X X X Cabin Pressure Differential Indicator 2,400 X X X X X X Rate of Climb, Cabin Indicator 2,400 X X X X X X Altitude Selector 5,000 X X X X X X Valves, Control Bleed Air 3,000 X X X X X X Emergency Pressure Shutoff Valve OC X X X X X X Temperature Control Valve 3,000 X X X X X X Shutoff Valve OC X X X X X X Discharge Valve 3,000 X X X X X X Emergency Pressure Controller 4,000 X X X X X X Cabin Pressure Indicator 2,000 X X X X X X Air Drier OC X X X X Dump and Fresh Air Valve OC X X X X X X Pressure Differential Switch OC X X X X X X Temperature Sensors, Low and High Limit OC X X X

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Water Extractor OC X X X X X X Heat Exchanger OC X X X X X X Auto Pilot System - Chapter 22 OC X X X X X X X Amplifier, Computer OC (BC per * next page) X X X X Trim Coupler OC X X X X Effective date ____________________ Page 5 of 15

OPERATIONS SPECIFICATIONS

AIRCRAFT MAINTENANCE HFB 320 HANSA JET

OVERHAUL PERIOD INSPECTIONS HOURS OR YRS. PO MP A B C D E Auto Pilot System - Chapter 22 (Cont'd) Airspeed Sensor and Switch OC X X X X Vertical and Yaw Rate Gyros 3,000 X X X X Altitude Control OC X X X X Servo Drives 3,000 X X X X X X Controller, Pedestal 3,600 X X X X X X Computers, Steering OC X X X X X Emergency Disconnect Switch OC X X X X * Bench check in accordance with applicable Manufacturer's Overhaul Manual or equivalent instructions every 2,000 hours or 18 months, whichever occurs first.

Communications System, Chapter 23 OC X X X X X X X To be determined by assigned inspector.

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Electrical Power System

- Chapter 24 OC X X X X X X X Alternator 1,200 X X X X X X X Regulators OC X X X X X X X Current Transformers OC X X X X Volt and Ampere Meters OC X X X X X X X Inverters *1,000 X X X X X X X * Inverter Operating Time Starter Generator 1,200 X X X X X X X Battery OC X X X X X X X Contactors, Main, Battery, Generator OC X X X X Effective date ____________________ Page 6 of 15

OPERATIONS SPECIFICATIONS

AIRCRAFT MAINTENANCE HFB 320 HANSA JET

OVERHAUL PERIOD INSPECTIONS HOURS OR YRS. PO MP A B C D E Electrical Power System

- Chapter 24 (Cont'd) Relays, Feeder Protection OC X X X X X X Relay, Bus Transfer OC X X X X Relay, Reverse Current OC X X X X Equipment & Furnishings, OC X X X X X X X Chapter 25 To be determined by assigned inspector.

Dragchute OC X X X X X X X (Detail inspection 60-day deployed)

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Fire Protection System, OC X X X X X X X Chapter 26 (F/C every 24 months) Fire Extinguisher OC X X X X X X X Assembly P/N F2718E/MS33514 or 1526/M33514 "Inspections, hydrostatic test, and life limits will be accomplished as set forth in Part 173, Chapter 1, Subtitle B of CFR 49 currently in effect."

Check and Distributing 2,000/5 yrs X X X X X X X Valves Element, Sensing, APU 1,500/3 yrs X X X X X X X Engine EO X X X X X X X Extinguisher, Portable OC X X X X X X X "Inspections, hydrostatic test, and life limits will be accomplished as set forth in Part 173, Chapter 1, Subtitle B of CFR 49 currently in effect."

Flight Control System, OC X X X X X X X Chapter 27 Gear Boxes OC X X X X Effective date _____________________ Page 7 of 15

OPERATIONS SPECIFICATIONS

AIRCRAFT MAINTENANCE HFB 320 HANSA JET

OVERHAUL PERIOD INSPECTIONS HOURS OR YRS. PO MP A B C D E Flight Control System, Chapter 27 (Cont'd)

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Position Indicators: OC X X X X X X X Aileron Rudder Flap Trim Actuators:

Aileron 1,200 X X X X X Rudder OC X X X X X Elevator 4 years X X X X X Trim Switches: OC X X X X X X X Rudder & Aileron Elevator Shutoff Valves: 4 years X X X X Anti-Stall Computer OC X X X X X X X (BC 3,000 hours) Angle of Attack Sensor OC X X X X X X X Stick Shaker OC X X X X X X X Actuators: 2,400/4 yrs X X X X X X Flap Slat Speed Brake Stick Pusher Cylinder 5 years X X X X X X X "Inspections, hydrostatic test, and life limits will be accomplished as set forth in Part 173, Chapter 1, Subtitle B of CFR 49 currently in effect."

Fuel System, Chapter 28 OC X X X X X X X Relief Valves OC X X X X X Pump, Fuel Boost 1,200/4 yrs X X X X X X X Normal Emergency Effective date __________________________ Page 8 of 15

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OPERATIONS SPECIFICATIONS

AIRCRAFT MAINTENANCE HFB 320 HANSA JET

OVERHAUL PERIOD INSPECTIONS HOURS OR YRS. PO MP A B C D E Fuel System, Chapter 28 (Cont'd) Check Valves OC X X X X X Methanol Tank 1,500/5 yrs X X X X X X X Quantity Transmitters OC X X X X X Quantity Indicators OC X X X X X X X Fuel Check Valve (APU) OC X X X X X X Shutoff Valve (APU) OC X X X X X Hydraulic Power, OC X X X X X X X Chapter 29 Check Valves OC X X X X X Pumps 2,000 X X X X X X X Accumulators, Systems (4) 2,400/4 yrs X X X X X X X Accumulators, Nose Wheel Shimmy Damper 2,400/4 yrs X X X X X X X Air Pressure Regulator OC X X X X Reservoir OC X X X X X X X Filters, Element 600 X X X X X X Pressure Control Valve 2,400 X X X X Valves, Shutoff 2,400 X X X X X Valves, Relief OC X X X X X Hand Pump OC X X X X X X X Switches, Low Level, Low Pressure OC X X X X