How aircraft certification affects you as a pilot is often misunderstood. In this third and final part, I will explain why you should understand it. Even if it is just for your own aircraft, its critical to flight safety and your safety.
Many well-known aircraft in General Aviation are what we term ‘fully certified’. They are manufactured under an aviation authority known as an NAA (National Airworthiness Authority). Examples are CASA (Civil Aviation Safety Authority), EASA (European Aviation Safety Authority), FAA (Federal Aviation Administration) and the CAA (Civil Aviation Authority) such as in New Zealand and the UK. There are also other organisations administering certain functions under the various national airworthiness authorities that certify different aircraft types in the light sport aircraft and ultralight categories.
A good example of the differences is best demonstrated by considering some of the categories of aircraft. For example, Normal Category, Utility Category, Light Sport Aircraft and Ultralights. Let’s consider spin testing since it is an important certification requirement that gets a lot of attention. But use caution with regard to the amendment number of a regulation. They can change at any given time.
Normal Category (fully certified) Aircraft must meet a certification requirement for spin testing/recovery. The requirement is that they must recover from the spin in one rotation or 3 seconds, whichever is the longer, recovering within the second rotation.
For Light Sport and Ultralight aircraft the certification requirement is they must recover within one rotation or 3 seconds whichever is the longer and in not more than one additional turn. An example of the spin testing for Light Sport Aircraft is the United States, the American Society for Testing & Materials (ASTM) F2245
Example Excerpt (ASTM F2245)
4.5.9 Spinning: 4.5.9.1 For airplanes~placarded "no intentional spins," the airplane must be able to recover from a one-turn spin or a 3-s spin, whichever takes longer, in not more than one additional tum, with the controls used in the manner normally used for recovery. 4.5.9.2 For airplanes in which intentional spinning is allowed, the airplane must be able to recover from a three-tum spin in not more than one and one-half additional turn. 4.5.9.3 In addition, for either 4.5.9.1 or 4.5.9.2: (I) For both the flaps-retracted and flaps-extended conditions, the applicable airspeed limit and limit maneuvering load factor may not be exceeded. (2) There may be no excessive control forces during the spin or recovery. Reproduction authorized per License Agreement with Daniel Schultz (ASTM International): Tue Oct 26 14:16:20 EDT 2004 (. F 2245-04 (3) It must be impossible to obtain uncontrollable spins with any use of the controls. (4) For the flaps-extended condition, the flaps may be retracted during recovery. 4.5.9.4 For those airplanes of which the design is inherently spin resistant, such resistance must be proven by test and documented. If proven spin resistant, the airplane must be placarded "no intentional spins" but need not comply with 4.5.9.1-4.5.9.3.
What does this mean for you as a pilot?
The only difference between the fully certified aircraft and the LSA or Ultralight when it comes to spin testing is that there isn't any difference.
Aerobatic aircraft must meet the certification requirement for spin testing with much larger margins for recovery. Generally, aerobatic aircraft have been tested for 3-6 rotations for recovery.
If your aircraft has a placard that states ‘Intentional Spins Prohibited’ or words to that effect then there is a good reason. When your aircraft was spin tested it was tested to meet a standard, under controlled environments and conditions.
1. The pilot will generally be a qualified test pilot.
2. The aircraft is often a prototype set up for flight testing.
3. The aircraft will most often be fitted with an anti-spin parachute.
4. The pilot will have a means by which to jettison the aircraft in the event of the aircraft not recovering during testing.
5. The pilot will wear a personal parachute in the event they have to abandon the aircraft.
6. The flight testing will be conducted in a specific geographic area in order to prevent injury or damage to other persons or property.
7. There will be a flight test schedule by which this testing is conducted in order to gather data.
8. There will be emergency services on standby.
9. Most importantly they know what they are doing and fully understand the risks.
Spin testing of aircraft is an activity that is not taken lightly by manufacturers and is a costly and serious high-risk test. If an aircraft type fails to meet the requirements for spin recovery then they are required to either address the design issues or have an ‘Alternative Means of Compliance’. This is often in the form of fitting the aircraft with a Ballistic Parachute.
Image from BRS Aerospace
There are several considerations for you as a pilot.
1. When your aircraft was spin tested, how did it behave after it met the requirement for spin recovery? You don’t know which is the point!
2. If you exceed the limitations set by the manufacturer you are essentially ‘playing with fire’! and more to the point 'dicing with death' The limitations are set as part of the certification and flight testing process for a reason.
NOTE: Unless a greater number of turns are requested for certification, acrobatic category airplanes have not been tested for more than six turns. The recovery characteristics for additional turns are unknown. (FAA AC 61.67C)
This accident occurred with a student and instructor on board engaged in stall recovery training. Unfortunately, this is too often a reality.
402. PILOT AWARENESS. The pilot of an airplane placarded against intentional spins should assume that the airplane may become uncontrollable in a spin. In addition, stall warning devices should not be deactivated for pilot certification flight tests in airplanes for which they are required equipment. (FAA Ac 61.67C) |
When engaging in stall spin activity, be it personal practice or time with a flight instructor, consider carefully the limitations of your aircraft and those of yourself and your instructor.
Your aircraft Approved Flight Manual or Pilot Operating Handbook will give you the information you need and the aircraft limitations, apart from a lot of great information that is often not explored by a pilot and/or aircraft owner.
Respect those limitations and your aircraft certification as the limits are there for a design and performance reasons. Certification is important to understand because it is the standard your aircraft has been manufactured to and the flight limitations and flight envelope for the aircraft.
When it comes to certification, spin testing serves to be a great example of its importance. If you wish to push limits with your flying, then go aerobatic and have the extra margins that are built into the aircraft design and hence flight envelope.
If we engage in training activities or manoeuvres that ‘push’ those limits then consider this:
Are the conditions the same as when your aircraft type was tested for stall and spin
recovery? Is it windy, turbulent, or a hot day?
Do you have the same experience as the test pilot who flew the aircraft?
Is the weight & balance exactly the same as the flight test aircraft?
Were there two occupants in the aircraft at the time of flight testing?
Was the aircraft configured the same as the flight test aircraft under the same conditions?
Do you have all the safety equipment that the test pilot and flight test aircraft had?
What was the height, location and air density at the time of testing?
Is your aircraft fitted out the same as the flight test aircraft ?
The above are just some of the considerations. Should your manoeuvre go ‘wrong’ then you are essentially now a test pilot or your instructor is. Is this what you signed up for?
There is the established flight envelope for your aircraft and there are prescribed limitations. Adhere to them and stay safe. Respect those limitations and your own.
Finally, consider this: If recovery from a manoeuvre is mishandled by a student or instructor or pilot skill building - is the aircraft going to recover?
Understand what you can and cannot do with your aircraft, or the aircraft you are about to purchase. This way you won’t be disappointed and you and anyone in your aircraft will stay safe! And more importantly you will enjoy safe flying more many years to come.
If you are interested in understanding more on this subject, worthwhile reading to further expand your knowledge of this important issue is :Stall / Spin Awareness by Rich Stowell.
Lorraine MacGillivray
CASA Authorised Person
Chief Flying Instructor
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