What Makes Up the Inspection Program for Turbine Aircraft? Part 2 of 3

Sept. 1, 2001

What Makes Up the Inspection Program for Turbine Aircraft?

Part 2 of 3

By Joe Hertzler September 2001

In the July 2001 issue of AMT, we discussed in detail the difference between an annual inspection and the inspection program required for multi-turbine powered aircraft. In this article, we will dissect the "inspection program recommended by the manufacturer" as required by 14 CFR Part 91.409(f)(3).

14 CFR Part 91.409 (e)
(e) Large airplanes (to which Part 125 is not applicable), turbojet multi-engine airplanes, turbopropeller-powered multi-engine airplanes, and turbine-powered rotorcraft. No person may operate a large airplane, turbojet multi-engine airplane, turbopropeller-powered multi-engine airplane, or turbine-powered rotorcraft unless the replacement times for life-limited parts specified in the aircraft specifications, type data sheets, or other documents approved by the Administrator are complied with and the airplane or turbine-powered rotorcraft, including the airframe, engines, propellers, rotors, appliances, survival equipment, and emergency equipment, is inspected in accordance with an inspection program selected under the provisions of paragraph (f) of this section, except that, the owner or operator of a turbine-powered rotorcraft may elect to use the inspection provisions of § 91.409(a), (b), (c), or (d) in lieu of an inspection option of § 91.409(f).
Simply stated, there are two basic requirements in this regulation for these more complex aircraft (Large and Multi-turbine powered). We must:
• Comply with replacement times for life-limited parts
• Comply with required inspection of the aircraft and all of its components

Hierarchy of inspection / maintenancerequirements
There are several misconceptions about what actually makes up the requirements for life-limited parts and the inspections to be performed. In order to simplify and help clarify the issue, we put together a hierarchy of aircraft inspection/maintenance requirements. In this hierarchy, we also include Airworthiness Directives simply because they are an integral part of the inspection and maintenance program for an aircraft and, although they are not specifically referenced in § 91.409, they are included by regulation through 14 CFR Part 39.
Each level within our hierarchy has its own criticality or level of importance, the first level being the most critical, and the last level being the least critical. The hierarchy is found in the table on page 92 and shows the origins of different types of requirements. In some cases, the same requirement will be contained in two different documents. The reason for the hierarchy is to show which document reference takes precedence over the other.
Now, lets look back again at § 91.409 (e). We know that we are required to replace life-limited parts and where we can find out what that list looks like. We also know that we are required to comply with "inspections recommended by the manufacturer" and where to find those inspection requirements. Reading a little further, we find that the rule does not just refer to the airframe. The rule also references the engines, propellers, rotors, appliances, survival equipment, and emergency equipment.

A common misconception
A common misconception is that the airframe manufacturer is the king of the aircraft’s inspection requirements including all components and equipment. Some might say that we don’t really have to look into the engine, propeller, rotor, appliance, survival equipment, and emergency equipment manufacturers inspection requirements when performing inspections on the aircraft.
Well, don’t fall into that trap. If you look closely into the airframe manufacturer’s inspection program, you will usually find a reference to other manufacturers’ inspection programs. Even if you don’t, you need to refer to those inspection and maintenance requirements as a part of the complete maintenance program for the aircraft.
This has been such a misunderstanding, even within the ranks of the FAA safety inspectors, that FAA headquarters in Washington issued very specific guidance information for clarification.

Excerpt from FAA Order 8300.10, Volume 2, Chapter 36, Section 1
C. Large Airplane (Over 12,500 lbs.) and Turbine Powered (Turbojet and Turbopropeller) Multi-engine Airplane Inspection Programs. These aircraft must be inspected according to the requirements of an inspection program selected by the owner/operator. FAR § 91.409(f) outlines various options available to the owner/operator.
(1) It may appear that some of the options specified in FAR § 91.409 (f)(1) through (3) do not involve the field inspector, as they refer to previously approved and manufacturer recommended programs. However, inspectors should recognize that these programs must be either currently recommended by the manufacturer or currently in use by the airline, air taxi, or FAR Part 125 operator supplying the program. This requirement is intended to prevent use of obsolete programs.
(2) Reference to a manufacturer recommended program has led to several misconceptions as to what precisely constitutes such a program.
(a) FAR § 91.409(f)(3) states, "A current inspection program recommended by the manufacturer." No reference is made to the aircraft manufacturer specifically. FAR § 91.409(e), however, requires inspection of the airframe, engines, propellers, appliances, survival equipment, and emergency equipment.
(b) A complete manufacturer’s recommended program therefore consists of the program supplied by the airframe manufacturer and supplemented by the inspection programs provided by the manufacturers of the engines, propellers, appliances, survival equipment, and emergency equipment installed on the aircraft.
NOTE: Because this program addresses inspections only, it does not include service bulletins, service letters, service instructions, and other maintenance documents.
It is important to understand the context of the FAA’s statement here. This is guidance information provided to all FAA safety inspectors to give instruction on how to perform a surveillance action on an aircraft operator operating under Part 91 when evaluating compliance with the required inspection programs.
Because of the detail required by the regulation, it is clear that not only do we need a hierarchy of inspection and maintenance requirements for the aircraft manufacturer, we also need to look deeper into other manufacturer’s requirements when determining what inspections and maintenance need to be accomplished.
Compiling a list of required inspection and maintenance items for a large or multi-turbine powered aircraft can be quite a task. The list of requirements for a typical King Air, for example, can be 900 items long. For a Hawker or Falcon, 1,300 items long.

Mandatory vs Optional for Part 91 operators
For Part 91 operators, the requirement is to INSPECT in accordance with the selected inspection program. Ref. § 91.409 (e) above. By definition (Ref CFR Part 1), maintenance includes inspection; however, inspection is not defined to include maintenance. With this in mind, to inspect an aircraft in accordance with an inspection program does NOT include lubrication, overhaul, replacement of non-life-limited parts, etc. The inspection requirement for Part 91 operators is to successfully complete all inspections required by the selected inspection program and correct any unairworthy discrepancies.
Simply stated, if the specific requirement calls for inspection, the item is mandatory; if the specific item calls for something other than inspection, it is simply a recommendation from the manufacturer.

Excerpt from FAA Headquarters Memorandum
An FAA memorandum dated March 5, 1984 states, "The national policy regarding these inspection programs holds that they involve inspection only. Maintenance is not required and should not be part of an inspection program.
When a manufacturer believes that special maintenance, parts replacement at specified intervals, or overhaul is required at a specific interval, the requirements should be made part of the type certificate data and appear in the type certificate data sheet, or limitations section of the maintenance manual."
We strongly encourage compliance with all recommendations, regardless of regulatory requirements. Other considerations are insurance policy details and unexpected downtime. One of the most expensive costs to an aircraft operator is unexpected or unplanned downtime.
Next month, we will continue our discussion regarding inspection programs and see how placing an aircraft on an Air Carrier Certificate will impact the requirements of an inspection program.

Table of Hierarchy of Inspection & Maintenance Requirements

Requirement Type
Comments and Example(s)
Type Certificate Data Sheet
Life Limited Parts
Look at the end of the applicable type certificate data sheet. That is usually referred to as "Data Applicable to all Models". In this area you will find either specific part numbers for parts that are required to be replaced as particular intervals or reference to the document that contains the information.
Airworthiness Limitations
Life Limited Parts
If the CDS does not list the life-limited parts individually It will refer to other documents, often the Airworthiness Limitations section of the maintenance manual. The Airworthiness Limitation section of the maintenance manual is usually Chapter 4. This is also most commonly the only chapter of the maintenance manual that is actually FAA Approved. Such approval is designated by FAA signature.
Airworthiness Directives
Inspections / Modifications and Life Limited Parts
Airworthiness Directives are amendments to regulation 14 CFR Part 39. Each is issued as an amendment.
Referenced Service Information
Life Limited Parts
Often the TCDS refers to service bulletins that contain the lising of life-limited parts. Such reference is as if the service bulletin is a part of the TCDS and therefore these bulletins are not optional.
Inspection Manual(s)
Required Look-Phase Inspections and Special Inspection
Inspection manuals make up the core of the inspection program. They include both Look-Phase inspection (multiple item inspections) and special inspections (single item inspections).
Maintenance Manual(s)
Required Look-Phase Inspections and Special Inspections and manufacturer recommended replacement times for parts
Some manufactures do not issue a separate inspection manual. In those cases, the Look-Phase inspections and the special inspections are contained in the Maintenance Manual (usually chapter 5) along with other maintenance and servicing recommendations such as lubrications and overhaul/replacement recommendations.
Service Information
Manufacturer Recommended Inspections and Modifications
Service information contains modifications and improvements to the product recommended by the manufacturer. Unless Service Information requirements are required by an Airworthiness Directive, they are optional to the aircraft owner. (MAN = Mandatory; OPT = Optional)