Part 135: Nine or Less?

May 9, 2006
FAA has suspended compliance with Handbook Bulletin HBAW 04-06, with the issuance of Revision E to the bulletin.

I am pleased to say that the FAA has suspended compliance with Handbook Bulletin HBAW 04-06, with the issuance of Revision E to the bulletin. This Handbook Bulletin deals primarily with the meaning of the term “type certificated” when used in 14 CFR Part 135.411. Part 135.411 is the air charter rule defining the difference between aircraft required to be maintained in accordance with a maintenance manual written by the air carrier, submitted to the FAA for approval, and approved by the FAA (See Sec. 135.415, 135.416, 135.417, and 135.423 through 135.443), fondly referred to as “10 or more” vs. the aircraft that is required to be maintained in accordance with the maintenance manual provided by the aircraft manufacturer, “nine or less.” The rule reads as follows:

14 CFR Part 135.411

(1) Aircraft that are type certificated for a passenger seating configuration, excluding any pilot seat, of nine seats or less, shall be maintained under Parts 91 and 43 of this chapter and Sec. 135.415, 135.416, 135.417, 135.421, and 135.422. An approved aircraft inspection program may be used under Sec. 135.419.

(2) Aircraft that are type certificated for a passenger seating configuration, excluding any pilot seat, of 10 seats or more, shall be maintained under a maintenance program in Sec. 135.415, 135.416, 135.417, and 135.423 through 135.443.

(b) A certificate holder who is not otherwise required, may elect to maintain its aircraft under paragraph (a)(2) of this section.

(c) Single engine aircraft used in passenger-carrying IFR operations shall also be maintained in accordance with Sec. 135.421 (c), (d), and (e).

In Handbook Bulletin HBAW 04-06E, the FAA has “clarified” its interpretation of the term “type certificated” as it pertains to Part 135.411 as well as furthered that cause toward elimination of field approvals for major alterations.

Excerpt from Handbook Bulletin HBAW 04-06E: Why is this bulletin being released? The Aircraft Maintenance Division, AFS-300, has determined that there are inconsistencies between different Flight Standards District Offices (FSDO) as to the placement of certain aircraft under the applicability of § 135.411(a)(1) vs. § 135.411(a)(2). These inconsistencies are from the lack of clarity in current guidance as it pertains to Supplemental Type Certificates (STC) or “other approved data” that reduce/restrict the seating capacity for aircraft to nine or less passenger seats.

For as long as I can remember the determining factor for whether an aircraft was a nine or less aircraft or a 10 or more aircraft was the number of seats within the aircraft eligible to be occupied during takeoff and landing. Even though the new Handbook Bulletin agrees with this over simplification:

Excerpt from Handbook Bulletin HBAW 04-06E: … One method to verify this is by the simple counting of seats installed in the aircraft …

The question elevated by this bulletin is that of how the seating configuration was approved for that aircraft. Part 135.411 is one of the few rules that, in my experience, was actually viewed the same at nearly all field offices, regional offices, and at headquarters in Washington, until recent years. Then something happened.

As I mentioned earlier, there has been, and continues to be, a huge push by the FAA to reduce or completely eliminate the field approval process. Without getting into too much detail, the field approval process was the long-standing primary method used to obtain approval for aircraft major alterations by the maintenance community. Maintenance people (IAs, A&Ps, repair stations) communicating and working collaboratively with maintenance people (FAA Flight Standards Division personnel, FSDO inspectors). The FAA is consciously replacing this process with the Supplemental Type Certificate (STC) process which is handled exclusively by the engineering division of the FAA known as Aircraft Certification. To complicate things, there seems to be a chasm between the Flight Standards Division of the FAA and the Aircraft Certification Division. Not just on policy and regulatory interpretation, but also relative to communication between divisions.

It seems that as new field inspectors began to take over the oversight of various certificates around the country due to reassignment or to cover for retiring safety inspectors, they began to ask questions about the operations that had not been asked before. They started to see instances across the country where operators had placarded seats “Not to be occupied during take-off and landing” or “For Crew Only” to reduce the number of seats for the purpose of keeping the air carrier simple (nine or less). In other cases, operators removed seats, to obtain the same result, nine or less. There were also instances where the aircraft’s interior was re-upholstered, and the interior was simply rearranged to fit a nine or less configuration. These steps, in and of themselves, are not the problem. The problem comes when the safety inspector goes to look at the paperwork, the authority to perform the changes.

Because of the push to eliminate the field approval process and replace it with the STC process, when the safety inspectors find the paperwork that supports these placards and seating configuration changes, they are obliged to ensure that are supported by an STC. This obligation is further underlined by HBAW 04-06. The new position of the FAA is that field approvals are no longer any good and do not properly “approve” the aircraft for service. This continues to permeate from the FAA even though Parts 65 and 145 continue to require only “Approved Data” to support approval for return to service following a major alteration, not necessarily an STC. The elimination of the field approval process is really a whole other subject, but nonetheless, I believe the primary driver on the FAA’s part for its new position on Part 135.411.

In defense of the FAA, there are most certainly cases where the air carrier did not seek any type of approval for these placard and configuration changes. In those cases I would assume that a more direct approach would have been sufficient to get the air carrier to comply with the rules.

Lets take a closer look at the handbook bulletin itself:

Excerpt from Handbook Bulletin HBAW 04-06E: A. Reduction of the TC’d passenger seating configuration may be accomplished by changing the aircraft’s approved seating configuration. This change could be a major change to the type design (14 CFR Part 21, § 21.93). As with any major change to the type design, the change must be done in accordance with an STC (Part 21, § 21.113) or an amendment to the TC (Part 21, § 21.97). In some instances, the removal of a seat in an aircraft may not constitute a major change to the type design. However, a type certificate data sheet (TCDS) for an aircraft may permit a maximum number of passengers that is greater than the “nine or less” limit established for § 135.411(a)(1). If the aircraft TCDS allows more than the nine passenger limit established for § 135.411(a)(1), then the FAA requires either the manufacturer’s amendment to the TC, or an STC for an interior layout, to define an eligible seating configuration to qualify under § 135.411(a)(1). Reducing an aircraft’s seating capacity to qualify under § 135.411(a)(1) by any other method will not be acceptable.

In this paragraph the FAA states that reduction of the passenger seating configuration “could be” a major change to the type design. I am certain they were very careful not to say “is a major change in type design”. This is significant because of the definition of what would make the change a “major” change found in Part 21:

14 CFR Part 21.93
Classification of changes in type design.

(a) … changes in type design are classified as minor and major. A “minor change” is one that has no appreciable effect on the weight, balance, structural strength, reliability, operational characteristics, or other characteristics affecting the airworthiness of the product. All other changes are “major changes” …

In order for removal of seats to constitute a major change the removal would have to have an appreciable effect on the airworthiness of the aircraft. In most cases this is highly unlikely.

Reading further in paragraph A of the Handbook Bulletin we see the position of the FAA is that if the TCDS permits a maximum number of passengers that is greater than the “nine or less” then the “FAA requires” the TC be amended or an STC be issued to define an eligible seating configuration. I believe that this is really a mixing of regulatory intentions and as written in the Handbook Bulletin is misleading.

There is a regulatory basis for requiring an amendment to the TC or STC to define a seating configuration when the TC does not specifically address the issue. This is often the case for aircraft that are delivered green and run through a completions center to receive a standard (TC’d) or customized interior configuration (STC). However, as I see it, there is no regulatory basis to require an amended TC or STC for an aircraft already in service with an approved interior configuration to reduce the number of seats to nine or less except as required by Part 21.93; A “major change” in type design.

The FAA’s position on a change in type design as it pertains to maintenance has shifted from a maintenance point of view to a manufacturing point of view. The ambiguity of Part 21.93 and its definition of a major change in type design creates hours and hours of conversation and debate. However, it seems obvious that in order for the removal of seats from an existing “approved” configuration to constitute a major change in type design as defined by Part 21.93, the removal would have to force a change in the CG range for the aircraft, or have some effect on the aircraft’s structural integrity. Again, highly unlikely.

To summarize, issuance of Handbook Bulletin 04-06 is another nail in the coffin of the field approval process, but the magnitude of the impact is a bit out of proportion. A high percentage of the aircraft operating under Part 135 as nine or less have an approved seating configuration for nine or less. If you are not sure of how the interior is approved, dig deeper. In most cases, there is an approved configuration from the TC and the aircraft was delivered as such. For those who will be forced to obtain an STC, the FAA has agreed to an expeditious process of issuing what is referred to as a one time STC. This will be helpful. FAA rulemaking is underway to change Part 135.411 to remove “type certificated” and replace it with a more practical term. The rulemaking process is long and tedious but we are hopeful to see a change before the end of 2006.

About the Author

Joe Hertzler