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Annual Inspections

Annual Inspections: “Aren’t They All the Same?"

Just like my previous blog on Pre-Purchase Inspections the term “Annual Inspection” can be vastly underrated.

With an Annual Inspection, there are basic guidelines that one needs to adhere to and at minimum a “check-list“ with mandated inspection points is required or needs to be followed. This check-list is still no guarantee that the aircraft hasn’t had any hidden damage or internal failing components.

Essentially, even an Annual Inspection may not reveal all of the problems an aircraft may have and it can still be considered "Airworthy" in the eyes of the FAA. I’ve already covered several of these points in the “Pre-Purchase” blog, however, it applies to Annual Inspections just as it does with many maintenance tasks or inspections accomplished in aviation.

The quality of the product in many cases is only as good as the person or persons involved.

Specific knowledge of the particular Aircraft Model is paramount with an intimate knowledge of weak or hidden areas, and common wear items.

If there is no other takeaway from this writing let the above statements resonate. Just because an individual has intimate knowledge of “Brand-X” and is proficient with a certain model or type aircraft it does not give them a broad stroke of working knowledge on any aircraft that crosses their path. I find this to be the number one area of degradation found overall in general aviation and throughout the industry worldwide.

This can be taken a step further with currency on model specifics. There are aircraft that I would not hesitate to perform inspections & work on 10-20 years ago. Today, however, I would not consider this because I am no longer familiar with the specifics and detailed changes since my last currency.

Do all Annual Inspections include Service and Maintenance?

The short answer is no and here is why. The additional performance rules governing the Annual Inspection are found in FAR 43.15 (C) 1, 2 that references using a checklist & minimum operating Engine parameters to be verified. Again, no service or maintenance discussed. Only requirement is that all systems, components, and appliances must be checked to ensure proper installation and satisfactory operation.

Know your Inspection Program Criteria

There are several types of inspection programs that can be utilized. There are also several means in which these can be accomplished to include various signatures required for those records. Let’s start with one of the most commonly found inspection programs utilized today:

FAR 43, Appendix D

For most of General Aviation piston singles & many 6-8 seat multi-engine aircraft FAR 43 Appendix D is utilized which covers the “Scope and Detail of Items to be Included in an Annual and 100 Hour Inspection”.

Note that this is only a minimum listing of items one needs to “Inspect”. In fact, there is no mention of service whatsoever. The only item that does not mention inspection is item (a):

(a) Each person performing an annual or 100-hour inspection shall, before that inspection, remove or open all necessary inspection plates, access doors, fairing, and cowling. He shall thoroughly clean the Aircraft and the Aircraft Engine.

"Cleaning the Aircraft and the Engine". How many times is the initial step of an Annual Inspection found to be completely overlooked! It should be obvious to most why even the FAA found this to be of such importance to make it an initial basic step of the inspection process. How many maintenance providers or more importantly, IA’s, completely omit step #1 is unconscionable.

If I look under sub-floors and see 40-50 years of untouched debris, rotten hydraulic hose, or OEM insulation undisturbed, then your aircraft hasn’t had an “Annual Inspection” in “x” number of years. How does one inspect an area that you cannot get a proper visual reference of?

The Manufacturer’s Service Manual Inspection Program:

Some manufacturers have their own inspection program and generally these provide not only specific inspection guidelines, but also include a detailed listing of “scheduled service items, lubrication, and maintenance items” that are to be conducted. You will also find a listing of “special tools” needed to properly maintain that aircraft. Many of these programs are “FAA Approved” as well.

Within these Programs are generally two categories, “Progressive Inspections” and “Scheduled Inspections”.

I will not go into further detail at this time regarding the difference between Progressive & Scheduled Inspection criteria, unless one is “for-hire”, a commercial operator, there are two shifts of maintenance personnel, then there is no benefit in changing inspection programs. There are also specific requirements involved when switching inspection programs as well.

Lastly, an FAA Approved Inspection Program

In general, these types of Inspection Programs are reserved for Repair Stations, Special Operations, Commercial Operations, Flight Schools, and those inspections that are documented & approved accordingly. An individual operator or IA can obtain such approvals, however, these would be very rare to find and for the average operator likely not much benefit in pursuing.

In Summary,

Based on the various types of Annual requirements above you can see where Lubrication and Service items may or may not be accomplished during the Annual Inspection itself. In accordance with FAR 43 Appendix D, one only inspects the aircraft and no service is required. When inspections are accomplished IAW the Service Manual (Chapter 5) this generally has requirements for Special Inspections, Lubrication, & Service at predetermined intervals (generally 25, 50, 100, 200 hr) that also include 6 month & 12 month etc intervals.

It would stand to reason that if you have an Annual Inspection only IAW FAR 43 Appendix D without any other supplemental service items, then the aircraft is not being properly maintained IAW the manufacturer’s recommendations. As an owner and/or operator it is your responsibility to assure that the aircraft is being properly maintained and kept in an Airworthy Condition.

Inspection Checklist

One is authorized to develop one’s own checklist as long as it covers the basic items addressed for the “Inspection Program” the aircraft is being utilizing for. FARs will allow an individual to utilize a checklist of one’s own design as long as it meets minimum areas of inspection listed in FAR 43 Appendix D as an example when the aircraft is inspected under this program.

The Manufacturers Service Manual has its own recommended criteria specifically designed for their individual product. Quite often, the aircraft manufacturer will include its own service and maintenance instructions for the engine and propeller included within its specific instruction.

There are separate inspection manuals generally from the engine manufacturer. The Propeller manufacturers also have specific inspection criteria. These manuals include more specifics and detail pertaining to the individual product in comparison to FAR 43 and the at times the Aircraft manufacturer’s criteria.

Furthermore, there are ICA’s. These are “Instructions for Continued Airworthiness” that are developed with specific criteria for modifications and alterations. Sometimes the OEM part is no longer available and an approved substitute part is installed requiring specific service instructions. These are often found with the STC copy and required to be in the aircraft records.

Logbooks & Responsibility

An aircraft may look outstanding in the logbooks but could be irrelevant in regards to the aircraft’s actual condition. Just the opposite could also be true, it may be an outstanding aircraft overall, with very poor records to reflect the condition and status.

The performance rules for the inspection itself can be found in FAR 43.11 Content, form, and disposition of records for inspections. These regulations pertain to the individuals authorized to complete the inspection and record-keeping required.

Note: FAR 43.11 covers Inspections Only.

All aircraft including “for-hire” aircraft need to be in compliance with FAR 91.409 Inspections criteria. Note that 91.409 state “no person may operate an aircraft”. This particular regulation covers “General Operating & Flight Regulations” therefore, applies to the responsibilities of the Owner-Operator.

Inspections, Service, or other Repairs accomplished at a FAR Part 145 Certified Repair Station (CRS) have their own set of rules & regulations associated with the record keeping. This is something that needs to be understood when it comes to Repair Stations during the Records & AD research as well.

One item worth mentioning regarding work orders and Repair Stations is performance rules regarding Maintenance, Repairs, & Overhaul. Work Orders have a completely different set of rules and regulations one must follow. Two key attributes to understand with work orders are:

  • A copy of the work order must be given to the Owner and is required to be a permanent part of the aircraft records in regards to a major repair.


Basically, an Annual Inspection is also a conformity inspection. This is to say that the aircraft not only meets the physical inspection criteria as previously discussed but it also meets several other areas of requirements.

Aircraft conforms to the TCDS “Type Certificate Data Sheet requirements”.

Airworthiness Directives are FAA mandated compliance items. This is where an updated & current configuration of the aircraft needs to be researched properly to assure all mandatory effective Airworthiness Directives have been properly complied with. This is often an overlooked area of Inspection if one only looks for newly released AD’s issued in the past 12 months in service since previous Annual. I have seen time after time where there is an AD for example, on a Magneto or Ignition Switch that is no longer installed in the aircraft. Similarly, if the engine is replaced with a factory new, Reman (remanufactured-zero time engines), or overhauled power-plant, then none of the previous AD compliance documentation is valid for that component.

Service Bulletins, these are not mandatory IAW and aircraft maintained under Part 43 “not for-hire” aircraft, however, these are pertinent documents that can help identify items that should possibly be verified during the Annual Inspection. These are Alerts from the manufacturer to aid in detection of possible defective items or failure modes identified in the field under certain conditions. Familiarization with the applicable Service Bulletins may not be mandatory; however, one should have an understanding of possible maintenance induced or engineering design deficiencies. It is not uncommon to see Service Bulletins that turn into an Airworthiness Directive if the item severity increases to a Safety of Flight level.

Supplementary Type Certificated (STC) modifications. All STC’s should have Instructions for continued Airworthiness if required. Since these alterations were accomplished to the aircraft after initial production & certification. The standard inspection and service requirements may no longer apply.

Repairs and Alterations:

Knowledge of any previous repairs and alterations is essential in determining airworthiness. The integrity of previous workmanship can impact the critical attributes of the aircraft’s primary components and/or structure.

Configuration changes require specific inspection requirements for additional kits installed. These modifications will not necessarily have specific instructions included in the standard manufacturer’s service manual. If these kits were provided by an STC holder for that alteration, then quite often these kits are sold over a time period to another “holder” and you need to do further research if the continued airworthiness instructions are not with the aircraft records.

Environmental Conditions

This is something many do not consider when performing an Annual Inspection. The environmental conditions have a direct impact on the inspection performance guidelines one should consider. This includes past operational history as well as future operating environment due to mission capabilities.

Coastal region-based aircraft in general may have corrosion issues not found inland. Aircraft in regions with high humidity levels in addition to a salt air environment require additional corrosion protection treatments, cleaning, and lubrication. If an aircraft is properly maintained with periodic corrosion treatments such as Corrosion-X or ACF, hangared, sometimes even humidity controlled environment, frequently cleaned, it can have little negative impact on an airframe. Tied down on an outside ramp in constant saturation on the other hand, is another matter altogether.

Aircraft in the radiating sunlight and dry climates may not see the corrosion problems above but this will rapidly deteriorate rubber seals, hose, and interior plastics/furnishings. If aircraft are stored outside in direct sunlight this will destroy not only the furnishings but also craze windows & windscreens, interior and exterior plastic-composites such as Wingtips & Flight Control tip fairings.

Aircraft operating off of grass airstrips & runways. This will introduce dirt & debris that will settle and build up throughout the airframe and compact in layers over a time period. Wheel fairings and brake components will need special attention at every maintenance-service interval to maintain proper working order. Same concept holds true for aircraft on ski’s for those with operations on snow or water.

The type of operating environment conditions need to be considered when inspecting each aircraft as the operating environment impact directly determines special inspection and service needs.

Kinds of Operations

The type of operations has more of an impact on the aircraft’s overall integrity than any other single consideration. In all cases the overall inspection, service, and maintenance guidelines should be critiqued to the aircraft mission profile that can directly determine how it is to be maintained.

A +14,000 hr Cessna 210 airframe utilized for operations such as low level, high turbulence commercial ground survey operations with additional wing tank extensions cannot be compared to a privately owned 1,500 hr hangared airframe in West Texas that is only operated 50-75 hrs a year.

In Summary

Was any other maintenance or service included with your Annual Inspection?

Note: FAR 43.11 covers Inspections Only

FAR 43.9 is the appropriate regulation for maintenance, preventive maintenance, rebuilding, and alteration records.

43.9 (a) specifically states:

(a) Maintenance record entries. Except as provided in paragraphs (b) and (c) of this section, each person who maintains, performs preventive maintenance, rebuilds, or alters an aircraft, airframe, aircraft engine, propeller, appliance, or component part shall make an entry in the maintenance record of that equipment containing the following information:

(1) A description (or reference to data acceptable to the Administrator) of work performed.

(2) The date of completion of the work performed.

(3) The name of the person performing the work if other than the person specified in paragraph

(a)(4) of this section.

Sometimes the IA signs off the “Inspection” portion of the Annual and a separate A&P may sign off the “Maintenance & Service” accomplished. If your logbook simply has a blanket stamp or logbook entry stating 100hr/Annual accomplished then when was the aircraft last serviced and maintained?

In general, when I see a generic stamp with the above 100 hr/Annual that aircraft is not being maintained at all in many cases. The only thing that is keeping that aircraft flying is the original Engineering design.

The type of operating conditions, initial aircraft condition, operating environment, and Pilot performance all have a direct impact on service, maintenance, and inspection standards. Simply stated, there is not a one-size fits all inspection application and these are the things one needs to consider when utilizing an Annual-12 month Inspection program.

When I hear or read statements like “it only took me 2 days for my Annual this year with no squawks”. I can only come up with two or three conclusions.

  1. There was a rubber stamp involved in that “Annual Inspection” and not worth the paper used to document such.

  1. There were 3-4 very skilled A&P’s working along with that IA for 2 days performing all the cleaning, service and maintenance.

  1. That aircraft is highly maintained, completely opened up and serviced throughout the previous 12-months. Come Annual inspection time, literally the “Annual” only consists of an open & close again inspection. This would suggest any needed maintenance was completed and all service items are up to the current date. All of the attaching hardware is in pristine condition.

You be the judge...

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