May 28, 2021, ©. Leeham News: After an overview of different certification rules and discussions about why there are different rule sets, we now exemplify the rules by looking at specific aircraft projects and how the certification rules affect the design.
We start this week with the idea to certify a 9-seat mini-airliner like the Tecnam P2012 Traveller. It’s a recent development with US-based Cape Air as the launch customer.
There are many aviation startups exploring opportunities in the air taxi or commuter market these days. Let’s examine some of the rules related to operations and product certification in this segment.
In the United States, commercial air transport operations are governed by either FAA 14 CFR Part 121 – Operating Requirements: Domestic, Flag and Supplemental Operations or Part 135 – Operating Requirements: Commuter and On Demand Operations and Rules Governing Persons on Board Such Aircraft. Examples of Part 121 operators include American, Delta, and United. Even their regional operators, such as Envoy (American Eagle), Endeavor (Delta Connection), and Air Wisconsin (United Express), operate under Part 121. These are very well-known brands and many of us travel with these airlines.
Part 135 operators are less well-known. They, such as Cape Air and Kenmore Air, provide either commuter (more than five scheduled round trips a week with some equipment restrictions) or on-demand services. While both types of operations are safe and heavily regulated, Part 121 operations come with additional regulatory overhead, crew requirements, and additional required airplane equipment.
Other countries structure their rules a bit differently. For example, the Canadian Aviation Regulations (CARs) divide similar types of operations into Air Taxi (703), Commuter (704), and Airline Operations (705). EASA, on the other hand, groups all commercial air transport operations into Part-CAT in the Commission Regulation (EU) No 965/2012.
From a product certification standpoint, the main rule for commuter aircraft is FAA 14 CFR Part 23 – Airworthiness Standards: Normal Category Airplanes. It covers aircraft with a maximum certified takeoff weight of 19,000 lb (8 618 kg) or less, with 19 passenger seats or less. There are four airplane certification levels within it:
Notable examples of Part 23 aircraft include Cessna 172, PC-12, Twin Otter, and HondaJet. With each certification level come shifting requirements. This distinction in Part 23, combined with the operator rules in Part 121/135 results in the need for a careful trade study if a designer wants to add extra seats (such as going above nine seats for operating economics).
Larger aircraft are certified based on FAA 14 CFR Part 25 – Airworthiness Standards: Transport Category Airplanes. It is the basis for many recognized aircraft ranging from E-145 to A380. Turboprops such as Dash 8 and ATR are Part 25 aircraft as well. Many purpose-built business jets, ranging from G650 to LearJet 45, are also in this category even though they typically have 19 passenger seats or less.
Now, let’s take a look at a real-life example. The Tecnam P2012 Traveller is Part 23 aircraft that was type certified by EASA in 2018 (Figure 1 and 2). It is a twin-engine, piston-powered, propeller-driven aircraft.
It has a maximum passenger seating capacity of nine and a maximum certified takeoff weight of 3 680 kg (8,113 lb). Would this product work as a “commuter” in the US, EU, and Canada?
|Operating Rule||Part 135||COMMISSION REGULATION (EU) No 965/2012, Part-CAT||CARs 703|
|Aircraft Limitation||Airplanes, other than turbojet-powered airplanes, having a maximum passenger-seat configuration of 9 seats or less, excluding each crewmember seat, and a maximum payload capacity of 7,500 pounds or less.||CAT covers all commercial operations. “Commuter” is not defined in Part-CAT.||A single-engined aircraft; a multi-engined aircraft, other than a turbo-jet-powered aeroplane, that has a MTOW of 8 618 kg (19,000 pounds) or less and a seating configuration, excluding pilot seats, of nine or less;|
Under Canadian Aviation Regulations, there is a clear set of rules (CARs 703) permitting the use of aircraft with nine passenger seats or less. This set of rules, as an example, allows operators to use an aircraft without a cabin attendant resulting in lower crew cost per trip compared to that of an airline operation.
EASA, as previously mentioned, structures its commercial operating rules differently. It does not specifically define “commuter operations”. Instead, it uses combinations of propulsion types, seating capacity, or maximum certified takeoff mass as thresholds for requirements. For instance:
“ORO.FC.200 Composition of flight crew
(c) Specific requirements for aeroplane operations under instrument flight rules (IFR) or at night.
(1) The minimum flight crew shall be two pilots for all turbo-propeller aeroplanes with a maximum operational passenger seating configuration (MOPSC) of more than nine and all turbojet aeroplanes.
(2) Aeroplanes other than those covered by (c)(1) shall be operated with a minimum crew of two pilots, unless the requirements of ORO.FC.202 are complied with, in which case they may be operated by a single pilot”,
Since there are many thresholds associated with nine passenger seats, the P2012 could bring benefits to EASA operators similar to those to Canadian operators.
The aircraft is also suitable for FAA 14 CFR Part 135 commuter operations. It is a non-turbojet-powered aircraft with nine passengers or less. This contributed to US Cape Air as the launch customer of the P2012.
We can see, from the analysis above, the importance of understanding both product certification and operating rules when developing an aircraft. In the next Corners, we will examine the pros and cons when adding a few seats.