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Block Lesson Four

Course Instructions

We have found people learn in different ways. Some learn better by reading the material themselves, others by watching a video. Throughout our Blocks we have the course set up in two different ways; 


  • The first is a video you can watch with text to speech. The video is an MP4 which is not interactive. There is no capability to link anything. That being said, any part that requires you to interact with, you will need to find the link in the text, or watch another video further down the page.
  • The second part is set up with text you can read with all FARs and documents linked to the FAA’s website. Everything is interactive. When it is time to interact with the FAA’s website, or watch another video the capability is there for you.


You can choose which way you would like to precede. 

NOTE:  Each block covers specific FAR information in chronological order, and it is recommended that you work through them in that order. However, you are free to work through them in any order you wish. These Block Lessons are FREE to anyone to read, and work through as often as you would like, all year round. The course can also be used as a TRAINING TOOL so that everyone in your organization is following the same processes.


If you would like to use this course to meet the 8 hours of learning required by FAR 65.93, you are required to complete ALL 8 blocks of Learning, and then take the Final Quiz. About 65% of the questions on the Quiz can be found in these block lessons, the rest you should know. Some of the questions on the quiz can only be answered by going through the course. The Quiz consists of 96 questions and you will need 70% to pass. If you don’t pass the quiz the first time, you will be able to take the Quiz again at any time. Once you start the Quiz you can pause it at any time, in order to search for information on the FAAs website, or review one of our Block Lessons. Once you have completed the Quiz and received at least 70% correct, you will be able to print a certificate to then submit to the FAA.

Block Lesson Four Will Cover

Part 23, being the historical aircraft certification basis by the FAA, to the production of type-certificated small aircraft prior to August, 2017. (All FAR links are to the historical Part 23, "Historical CFR")

Block Lesson Four Video

Inspection Authorization Refresher Training

FAR 23.1301 is important to an IA.

FAR 23.1301 is important to an IA because it requires that each piece of installed equipment must be appropriate for its intended function, and it must work. It also needs to be appropriately identified as to what it is, what it does, and how it does it. When an IA accomplishes an Annual or Progressive inspection, all installed equipment must be inspected in accordance with FAR 43, Appendix D. This includes any equipment installed and approved under FAA Form 337 Major Repair and Alteration too.

FAR 23.1303 is important to an IA, It defines what specific navigation instruments are always required, even for simple Day-VFR.

For example, an airspeed indicator, altimeter, and a compass are always required, and they must work. Notice that FAR 23.1303 only requires a simple altimeter, not a sensitive altimeter adjustable for barometric pressure as is required by FAR 91.205 for IFR operations. However, to be legal, the altimeter installed must meet the aircraft Equipment List and the aircraft IPC to be airworthy. In other words, a simple altimeter might be legal to be installed in an old Stearman or Taylorcraft, but would not be legal in a Piper Cherokee or Cessna 172.

FAR 23.1305 is important to an IA because it defines what powerplant instruments are required to be installed and working as a minimum for Day-VFR.

FAR 23.1305 is important to an IA because it defines what powerplant instruments are required to be installed and working as a minimum for Day-VFR. These common sense instruments are required for each installed engine such as fuel quantity indicators, oil pressure and oil temperature indicators, tachometers, and a cylinder head temperature gage for aircraft with cowl flaps. If any of these instruments or indicators does not function, the aircraft is not legal to fly.

FAR 23.1321 is important to an IA because it defines the actual panel arrangement of the primary navigation instruments on FAR 23 aircraft.

This is one area where FAR 23 is different than CAR 3. On FAR 23 aircraft the primary navigation instruments must be installed on the pilot’s side panel in a “T” formation: the attitude indicator must be in the top position in the middle between the airspeed indicator to the left and the altimeter on the right; the directional gyro must be directly under the attitude indicator. 


In CAR 3 aircraft these indicators can be installed anywhere on the panel unfortunately. Specifically, in older aircraft,  you will find these instruments in varying positions in different models such as older Bonanzas, Comanches, early Barons and the like. This is another reason that it is critical for an IA to initially determine the Certification Basis of an aircraft prior to accomplishing any required inspection on it.

FAR 23.1327 is very important to an IA accomplishing an Annual or Progressive inspection.

FAR 23.1327 is very important to an IA accomplishing an Annual or Progressive inspection. Every CAR 3 and FAR 23 aircraft must have a functioning magnetic direction indicator, a compass, installed as a minimum for Day VFR flight. This FAR defines the deviations allowed for the installed compass. Further, each installed compass must be accompanied by a deviation card or placard indicating the deviation on each of the required tested compass headings. If the deviation information required is missing, the aircraft is not airworthy and illegal to fly.

FAR 23.1357 Defines what circuit protective devices are required on electrical circuits.

FAR 23.1357 is very important to an IA because it defines what circuit protective devices are required on electrical circuits, such as circuit breakers and fuses, and the minimum amount of spare fuses required if fuses are used.

FAR 23.1361 is very important to an IA because it defines the specific requirements and limitations of master switches.

It specifies that master electrical switches be capable of disconnecting from the electrical system in flight of power distribution systems such as generators and alternators. This is why you will normally find split master switch rockers in CAR 3 and FAR 23 aircraft. This FAR also allows certain circuits to remain powered even if the engine is not operating to keep such items as digital clocks in operation. It must be remembered that any equipment so energized will ultimately deplete the battery charge over long periods of time.

FAR 23.1365 is very important to an IA because it defines the use of electrical cables and wiring used in aircraft.

FAR 23.1365 is very important to an IA because it defines the use of electrical cables and wiring used in aircraft. An IA inspecting and approving a Major Alteration involving the addition of electrical equipment should pay particular attention to this FAR. An IA should always assure that no electrical wires ever are located under any fluid-carrying line, and the electrical wiring is appropriate to the amount of current being carried. Always refer to the wire chart in AC 43.13-1B when any question arises.

FAR 23.1367 defines the required labeling for each switch in an aircraft, and what equipment it controls.

FAR 23.1367 is very important to an IA because it particularly requires that each switch in an aircraft be identified as to what equipment it controls, and how it operates such as open and close, or up and down for example indicating either on or off.

FAR 23.1541 is very important to an IA because it defines the general requirements for markings and placards installed in an aircraft.

These requirements include where they should be displayed, that they must not be easily erased, defaced, or obscured. When an IA accomplishes an Annual or Progressive inspection, attention must be paid to all required markings and placards required by FAR.

FAR 23.1543 is very important to an IA because it defines how instrument markings should be applied to such instruments as an airspeed indicator for example.

In older Bonanzas, where the airspeed had to be restricted under an Airworthiness Directive until a modification was installed, the red line had to be marked on the cover glass of the instrument at a reduced airspeed. It required an alignment stripe from the cover glass onto the housing of the instrument to assure the glass did not move.

FAR 23.1545 is very important to an IA because it defines specifically how airspeed indicators must be marked.

An IA should always inspect the airspeed indicator when accomplishing an Annual or Progressive inspection because owners and operators sometimes find it advantageous to them to install a different indicator than the original required one. A good example would be finding an airspeed indicator with a blue line on the face installed in a single engine aircraft. Such an indicator only is installed in a multiengine aircraft.

FAR 23.1547 States the legal requirement for the compass deviation placard to be installed. 

FAR 23.1547 is very important to an IA because it specifically states the legal requirement for the compass deviation placard to be installed. It also defines the limits that must be met when accomplishing a compass swing.

FAR 23.1549 is very important to an IA because it defines how powerplant instruments are to be marked.

AN IA should pay particular attention to the tachometer installed to determine if the red line is marked at the proper RPM, and if there should be any cautionary markings required due to tested vibration from the propeller. On many Pipers there is an area of RPM where it is restricted from continuous operation.

FAR 23.1555 is very important to an IA because it defines the requirements for control markings and placards.

Each aircraft control, other than the primary flight controls in the cockpit such as the yoke, rudder pedals, and the like, must be appropriately marked as to what they control and how. Good examples are fuel controls, mixture controls, throttle controls, landing gear controls, cowl flap controls, and the like.

FAR 23.1557 Defines the requirements to identify areas of the aircraft, other then the cockpit. 

FAR 23.1557 is very important to an IA because it defines the requirements to identify other areas of the aircraft such as placarding baggage areas with loading conditions, fuel and oil tank capacities, and emergency exit identification.

FAR 23.1559 Defines the required operating limitations placard and where it must be displayed.

FAR 23.1559 is very important to an IA because it defines the required operating limitations placard and where it must be displayed in the cockpit. If this placard is missing or is unreadable, the aircraft is not legal to fly.

FAR 23.1563 Defines the required airspeed limitations placard and where it must be displayed.

FAR 23.1563 is very important to an IA because it defines the required airspeed limitations placard and where it must be displayed in the cockpit. If this placard is missing or is unreadable, the aircraft is not legal to fly.

FAR 23.1567 is very important to an IA. 

FAR 23.1567 is very important to an IA because it defines the required flight maneuver limitations placard and where it must be displayed in the cockpit. It is very important to read them over carefully to become familiar with their differences. If this placard is missing or is unreadable, the aircraft is not legal to fly.

FAR 23.1581 Defines the requirement for having a current Aircraft Flight Manual in the aircraft and when.

FAR 23.1581 is very important to an IA because it defines the requirement for having a current Aircraft Flight Manual in the aircraft at the time IA approves the aircraft for return to service after accomplishing an Annual or Progressive inspection. The manual required is always found on the aircraft Type Certificate Data Sheet. An IA should always contact the type certificate holder to ascertain the current revision status.

FAR 23.1589 Defines the required weight and balance document that must be current.

FAR 23.1589 is very important to an IA because it defines the required weight and balance document that must be current and within the aircraft to legally operate. The actual document requirement is found in each Type Certificate Data Sheet.

End of Block Lesson Four

Now you have finished Block Four, and may review the remaining blocks in any order you would like. After reviewing all 8 blocks of learning, you are ready to take the quiz. I hope you have enjoyed, this lesson and have learned something that will help you and keep you out of trouble with the FAA.


Thank you for taking our Online Inspection Authorization Refresher Training Seminar!

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