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I understand that for Small Airplanes, the FAA establishes different categories, one of which is Normal, Utility, and Aerobatic, commonly known for their Limit Load Factors, which are:

  • Normal: 3.8 G, -1.52G

  • Utility: 4.4 G, -1.76G

  • Aerobatic: 6.0 G, -3.0 G

It's worth noting that these are categories for light aircraft, meaning those with a certified Maximum Takeoff Weight (MTOW) of 12,500 pounds or less. However, I have not found any official information from the FAA that takes these limits into account for the certification of the Normal category, only the MTOW. Upon further investigation in 14 CFR, I found that in Section 23.2005, it states that one of the requirements for the Certification of normal category airplanes is: "Certification in the normal category applies to airplanes with a passenger-seating configuration of 19 or less and a maximum certificated takeoff weight of 19,000 pounds or less." It also refers to which aerobatic aircraft may or may not be certified in the normal category, as can be seen in part (d), which is also weird because they are "different categories"

This appears to contradict the previously mentioned Normal Category, which allows aircraft of up to 12,500 pounds. Are they different categories despite having the same name? If someone can clarify this matter for me and, in case they find the official FAA requirements for the certification of Normal, Utility, and Aerobatic category aircraft, could they please share them with me? I would be immensely grateful

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https://www.faa.gov/aircraft/air_cert/design_approvals/small_airplanes/categories

https://www.ecfr.gov/current/title-14/chapter-I/subchapter-C/part-23/subpart-A/section-23.2005

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A "Normal" category aircraft certificated under 14 CFR Part 23 now includes Utility, Acrobatic and Commuter aircraft as of August, 2017. (See the Federal Register regarding this change and associated details).

As shown in your question 14 CFR 23.2005 states (in part):

(a) Certification in the normal category applies to airplanes with a passenger-seating configuration of 19 or less and a maximum certificated takeoff weight of 19,000 pounds or less.

Also, note from the Federal Register linked above: "This rule does not affect the category of existing airplanes, nor does it require the TCDS be revised or reformatted. Airplanes currently certified in the utility category for spin training retain that capability under this new rule. Furthermore, the airworthiness of the existing fleet will not be affected by this rule."(Source)

(emphasis is mine)

Your reference to "Small Airplanes" (in your question) comes from an outdated page on the FAA website.

See this previous question that provides additional information: What is the difference between a standard airworthiness and a experimental airworthiness certificate?

Hopefully, this should clarify any confusion you may have.

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Once upon a time, these commonly-quoted limit load factors were in 14 CFR § 23.337:

(a) The positive limit maneuveringload factor n may not be less than—

(1) 2.1 + (24,000 ÷ (W + 10,000)) for normal and commuter category airplanes, where W = design maximum takeoff weight, except that n need not be more than 3.8;

(2) 4.4 for utility category airplanes; or

(3) 6.0 for acrobatic category airplanes.

(b) The negative limit maneuvering load factor may not be less than—

(1) 0.4 times the positive load factor for the normal utility and commuter categories; or

(2) 0.5 times the positive load factor for the acrobatic category.

(c) Maneuvering load factors lower than those specified in this section may be used if the airplane has design features that make it impossible to exceed these values in flight.

This section was removed wholesale when part 23 was revised in 2017. There is no longer such a thing as "utility," "acrobatic," or "commuter" airplanes among newly certificated airplanes. There are only normal category airplanes, and the manufacturer has to show that its limit loads are sufficient for its intended use per § 23.2200(b):

The applicant must determine the structural design envelope, which describes the range and limits of airplane design and operational parameters for which the applicant will show compliance with the requirements of this subpart. The applicant must account for all airplane design and operational parameters that affect structural loads, strength, durability, and aeroelasticity, including [...] (b) Design maneuvering load factors not less than those, which service history shows, may occur within the structural design envelope.

The old categories are still relevant, since the vast majority of general aviation in use were certificated under the old rules and retain their legacy categories.

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  • $\begingroup$ It should be noted that a means of compliance to show that limit loads are sufficient for the intended purpose may use the earlier g loads defined for earlier category aircraft. The 2017 rewrite moved a lot of regulation text from the FARs to ASTM, which was then allowed to create new means of compliance in parallel with the FAR means. You are not going to be able to design an acrobatic aircraft with a 3g load. You will have to use 6g, some alternate from ASTM or spend a great deal of time proving to the FAA that whatever other number you select is suitable. $\endgroup$
    – Pilothead
    Feb 19 at 18:33

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