(6) Increased tendency to nose over during landing.
(7) Reduced stall warning margin, change in either aerodynamic stall warning characteristics (warning buffet) or reduced effectiveness of stall warning system, or both, in both level and turning flight with power either on or off, or both.
(8) Changes in stalling and stall recovery be havior in both level and turning flight with power either on or off, or both. Stalls may become more abrupt and altitude loss before recovery may increase.
(9) Increased tendency to enter an inadvertent spin and reduced ability to recover from the spin.
(10) Reduced longitudinal, lateral, and directional stability.
(11) Increased airframe vibration and buffet.
Tundra tires: 1) reduce the airplane's directional stability and controllability during takeoff and landing ground rolls, 2) increase its tendency to ground loop during takeoff and landing ground rolls, and 3) increase its tendency to nose over during landings on paved surfaces more than during landings on gravel, grass, or other surfaces that allow the tires to skid more easily.
c. Potential Propulsion Systems Effects
(1) Fuel flow may be affected by changes in normal flying attitude.
(2) Unusable fuel may be affected by changes in normal flying attitude.
(3) The fuel tank sump may be affected by change in ground attitude.
(4) Fuel drains may be affected by change in ground attitude.
(5) Engine cooling may be affected by performance or flying attitude changes.
(6) Changes in tires may affect the air induction system certification for operation on wet runways.
(7) Changes in tires that change ground attitude may affect the induction system icing protection.
6. CERTIFICATION OF TUNDRA TIRE S FOR USE ON LIGHT AIRPLANES The certification process for tundra tires is the same as for any other tire to be used in aviation.
a. A manufacturer may obtain a technical standard order authorization (TSOA) for the tire using the requirements in TSO-C62e. TSO-C62e contains minimum performance
57 standards for aircraft tires. The TSOA, which covers design and manufacturing of the tire only, is not an installation approval. The tire should be approved for installation on a specific airplane model either by TC, STC, or FAA field approval in accordance with HBAW 97-01B, “Flight Standards Handbook Bulletin for Airworthiness” or later revision. The applicable requirements for installation of a tire on a given airplane should be determined based on the original certification basis specified in that airplane's type certificate data sheet (TCDS). Developing a compliance checklist, as described in item 7 below, should be accomplished by the applicant and the FAA engineer.
b. An alternative certification method exists fo r a tire that does not have a TSOA. The tire design approval may be obtained concurrently with the installation approval for specific airplane models by TC or STC. The requirements of the TSO can be used for a determination of acceptable tire performance in such a project. The applicable requirements for installation of a tire on a given airplane should be determined based on the original certification basis specified in that airplane's TCDS. Developing a compliance checklist, as described in item 7, should be accomplished by the applicant and the FAA engineer. Before offering tires approved by this method for sale, the tire manufacturer would need a parts manufacturing approval (PMA).
7. COMPLIANCE CHECKLIST See Appendix 2 for an example of the "Compliance Checklist," to CAR part 3 as amended to November 1, 1949. This checklist is intended to show all aircraft certification requirements that could be affected by a tundra tire installation. Many of these requirements may be unaffected by a given installation. The compliance checklist for a specific installation should be determined at the start of a project. (See Appendix 2 in this section, which is applicable to § 23.733 Tundra Tires.)
58 APPENDIX 1
FAA TEST RESULTS/EFFECTS OF TUNDRA TIRES
ON THE HANDLING QUALITIES/STALLS/STALL CHARACTERISTICS OF THE PIPER PA-18
1. Tests Recent accidents in Alaska involving airplanes equipped with tundra tires prompted the NTSB to recommend to the FAA that they conduct flight tests to determine the effects of tundra tires on aircraft performance, stalls, and handling qualities. The following five tires were evaluated at various combinations of Center of Gravity (CG)/weight:
a. Factory installed (8.00-6).
b. McCreary Tundra Tires (8.50-10).
c. McCreary Tundra Tires (29x11.0-10).
d. Schneider Racing Slicks (14.0x32.0x15).
e. Goodyear Airwheels (35x15.0-6).
2. Results Quantitative/qualitative data obtained from testing the four tundra tires were compared to the data obtained from testing the factory-installed tire. The following is a summary of the findings:
a. Ground Handling Forward field of view during taxi is inversely related to tire size. As the tire size increases, the ability to see over the nose decreases requiring the pilot make “S” turns with the airplane. Ground handling during takeoff from a gravel runway is satisfactory for all configurations. Ground handling during landing on a gravel runway is also satisfactory for all configurations tested, although there is a noticeable nose down pitching moment when the tire(s) contact the ground. This is most obvious when making a main wheel only landing. Crosswind landings on runway 13 at Lake Hood Strip, a 2,200 feet x 80 feet gravel runway next to Lake Hood three miles southwest of Anchorage, Alaska, were demonstrated for tire configurations items 1a, 1b, and 1c in winds from 180 degrees (from ahead and to the right of the airplane at an angle of 50 degrees to its flight path) at 14 knots gusting to 16 knots.
The wind thus had a crosswind component of approximately 10.7 knots gusting to approximately 12.3 knots and a head wind component of approximately 9.0 knots gusting to approximately 10.3 knots. No crosswinds were available during tests for configurations d and e. No tests for ground handling were accomplished on paved runways. The ground handling characteristics of airplanes equipped with tundra tires
59 are known to be substantially poorer on pavement than on gravel, grass, and other surfaces that allow the tires to skid easily.
b. Performance Tundra tires adversely affect airplane performance. For example, the uncorrected average rate of climb (tested at 1.05 times maximum gross weight) for the standard tire was 526-feet per minute. The uncorrected average rate of climb for configurations items 1d and 1e (tested at 1.05 times maximum gross weight) was 449 and 464-feet per minute.
3. Stalls/Stall Characteristics
a. The purpose of the stall tests was to de termine whether there are any differences between the stalling speed and stall characteristics of a PA-18 “150” airplane equipped with tundra tires and the stalling speed and stall characteristics of the same airplane equipped with standard tires. The data obtained from the stall tests do not confirm the theory that tundra tires increase the PA-18 “150” stalling speed.
b. Stall characteristics (all configurations) are normal when the airplane is stalled in balanced flight. In a turning stall, the airplane rolls slowly to a near wings level attitude. In maneuvering flight, the tendency is for the nose to drop as the bank angle is increased. If the pilot uses top rudder (right rudder in a left turn) to compensate for this and then stalls the airplane, the airplane may roll rapidly over the top. This could result in a departure or the incipient phase of spin. If the airplane is maneuvering at low altitude when this sequence of events occurs (for example, while circling to spot moose), the airplane may impact the ground before recovery. Also, although washout was not varied during these flight tests, previous FAA experience has shown that stall characteristics are further aggravated when operators of the PA-18 remove the 2.5 degrees of washout at the wing tip, which is not an approved change. This condition will result in a rapid roll when the airplane is stalled during turning flight.
4. Handling Qualities For any given CG/weight, the lateral and directional stability deteriorates as tire size is increased.
5. Stall Warning
Installation of the artificial stall warning system on the PA-18 is optional. Most of the PA-18s in Alaska do not have the system installed. The airplane tested did have the artificial stall warning system, and several test points were obtained with the system deactivated. The airplane as tested does not have an aerodynamic stall warning.
APPENDIX 2
A "COMPLIANCE CHECKLIST" TO CAR PART 3, AS AMENDED TO NOVEMBER 1, 1949
Subpart B—Flight Requirements Weight Range and Center of Gravity
Section Subject
3.71 Weight and balance
3.72 Use of ballast
3.73 Empty weight
3.74 Maximum weight
3.75 Minimum weight
3.76 CG position
Performance Requirements—General
3.81 Performance *
3.82 Definition of stalling speeds *
3.83 Stalling speed *
Takeoff
3.84 Takeoff *
Climb
3.85 Climb *
Landing
3.86 Landing *
Flight Characteristics
3.105 Requirements * (exclude § 3.117)
Ground and Water Characteristics
3.143 Requirements*
61 Flutter and Vibration Section Subject
3.159 Flutter and vibra tion (vibration only)
* Indicates topics identified by NTSB Safety Recommendation A-95-13
Subpart C—Strength Requirements Symmetrical Flight Conditions (Flaps Retracted)
3.189 Airplane equilibrium
Flaps Extended Flight Conditions
3.190 Flaps extended flight conditions
Unsymmetrical Flight Conditions
3.191 Unsymmetrical flight conditions
Control Surface Loads
3.211 General
3.212 Pilot effort
3.213 Trim tab effects
Horizontal Tail Surfaces
3.214 Horizontal tail surfaces
Vertical Tail Surfaces
3.219 Maneuvering loads
Control System Loads
3.231 Primary flight controls and systems
Ground Loads
3.241 Ground loads
3.242 Design weight
3.243 Load factor for landing conditions
62 Landing Cases and Attitudes Section Subject
3.244 Landing cases and attitudes
Ground Roll Conditions
3.248 Braked roll
3.249 Side load
Subpart D—Design and Construction Control Systems
3.342 Proof of strength
Landing Gear
3.351 Tests
3.352 Shock absorption tests
3.353 Limit drop tests
3.354 Limit load factor determination
3.355 Reserve energy absorption drop tests
Wheels and Tires
3.361 Wheels
3.362 Tires
Brakes
3.363 Brakes
Subpart E- Propulsion Systems
3.429 Fuel System General
3.437 Unusable Fuel
3.444 Fuel Tank Sump
3.553 Fuel Tank Drains
3.583 Cooling Tests
3.605 Induction System General
3.606 Induction Systems de-icing and anti-icing provisions
Subpart F—EQUIPMENT Landing Lights
3.699 Landing light installation
63 Subpart G—OPERATING LIMITATIONS AND INFORMATION
3.735 General
Limitations
3.737.1.1 Limitations
23.735 Brakes
The corresponding rule in CAR 3 is CAR 3.363.
There is no corresponding airworthiness criteria in the Airship Design Criteria.
Original Issue and Subsequent Brake Replacement and Modified Parts
1. Related regulations and documents are:
a. Regulations Acceptable means of compliance are found in 14 CFR, part 23. Additional specific information is listed below, including other regulatory material and advisory information. Part 23 sections may be used in showing compliance with the corresponding sections of the former CAR for airplanes where the CAR regulations are applicable. For convenience, the former CAR section reference is also shown in parenthesis following the part 23 section reference:
Part 21, § 21.15 Applicati on for type certificate Part 21, § 21.93 Classification of changes in type design (TC)
Part 21, § 21.113 Requirement of supplemental type certificate
Part 21, § 21.303 Replacement and modification parts Part 23, § 23.55 Accelerate-stop distance Part 23, § 23.75 (3.86) Landing Part 23, § 23.143 (3.106) Controllab ility and maneuverability:
General
Part 23, § 23.231 (3.144) Longitudi nal stability and control Part 23, § 23.233 (3.145) Directi onal stability and control Part 23, § 23.493 (3.248) Br aked roll conditions Part 23, § 23.731 (3.361) Wheels Part 23, § 23.735 (3.363) Brakes
65 Part 23, § 23.1301 (3.652) Func tion and installations Part 23, § 23.1309 Equipment, sy stems, and installations Part 23, Appendix D Wheel spin-up and spring back loads
Part 23, § 23.1529 and Instructions for Continued Airworthiness Appendix G to Part 23
Part 135, Appendix A Additional airworthiness standards for 10 or more passenger airplanes
Part 45, § 45.14 Identificatio n of critical components
Part 45, § 45.15 Replacement and modification parts
b. Advisory Circulars (AC's) AC 23-8C “Flight Test Guide for Certification of Part 23 Airplanes.”
c. Technical Standard Order (TSO) TSO-C26d “Aircraft Wheels, Brakes and Wheel/Brake Assemblies for Parts 23, 27 and 29 Aircraft, with Addendum 1,” October 14, 2004.
d. Industry Documents SAE ARP 597D “Wheels and Brak es, Supplementary Criteria for Design for Endurance-Civil Transport Aircraft,” February 7, 2008.
SAE ARP 813B “Maintainability Recommendations for Aircraft Wheels and Brake Design,” February 1, 1995.
SAE AIR 1064D “Braking System Dynamics,” September 26, 2007.
SAE AS 1145B “Aircraft Brake Temperature Monitor System (BTMS),” February 1, 1998.
SAE ARP 1619A “Replacement and Modified Brakes and Wheels,” March 1, 2001.
2. Background
A review of recent replacement and modification wheel/brake system and installation approvals on part 23 airplanes has resulted in the need to provide FAA guidelines that clearly describe the changes and associated substantiation procedures involved. As contained herein, these guidelines will reflect on issues that have been identified by industry under ARP 1619A, which, in part, concerns the variance in compliance provisions associated with original equipment manufacturers (OEM) and non-OEM applicants. The guidelines will include: 1) a description of replacement or modified wheel, 2) wheel/brake parts or assembly changes, 3) a description and examples of associated "major" and "minor" changes, and 4) a description of corresponding laboratory and airplane flight tests needed to ensure that requested changes will result in a continued level of airplane safety and performance.
3. Classification of replacement and Modified Wheel/Brake Changes
a. Replacement of Wheel, Wheel/Brake Parts, or Assembly Changes
A replacement wheel, wheel/brake part, or an assembly change is classified as one in which either the included parts or assemblies that are being changed are of equivalent design. This will result in an equivalent level of certified type performance and safety to that shown by either the originally approved parts or assemblies. The change may be approved under a PMA by the provisions of part 21. Under part 21, § 21.303, an applicant may be eligible for approval of either PMA replacement parts or assemblies, or both, by showing compliance in accordance with the following methods, as applicable:
(1) Licensing Agreement
Applicant should provide evidence of a licensing agreement or equivalent with the holder of a TSOA, TC, or an STC with the submission of any design data covered by the licensing agreement, as determined by the FAA. See Order 8120.2G for procedure.
(2) Identicality
Applicant should provide evidence the parts he produces will be identical to the corresponding parts of an approved 14 CFR type design, TSO, or PMA. Data submitted should include all applicable design, material, and process specifications that is, technical data that would specify all dimensions, tolerances, materials, processes, and specifications to the design of the corresponding part of an approved design.
(3) Airworthiness Requirements (Tests and Analyses)
Applicant should provide evidence in the form of drawings, test reports, computations, and other substantiating data showing the part meets either the applicable part 23 airworthiness requirements or the certification basis under which the airplane was approved (see the following NOTE). See Order 8110.42C.
Compliance to applicable part 23 airworthiness requirements may include:
(a) Part 23, § 23.55 and Accelerate-stop distance for Part 135, Appendix A commuter cat egory airplanes and other airplanes that have accelerate-stop distance requirements, includi ng airplanes that have published data such as stopping distances and brake energy/cooling charts in the AFM.
(b) Part 23, § 23.75 Landing.
(c) Part 23, § 23.143 Controllabi lity and maneuverability:
General.
(d) Part 23, § 23.231 Longitudinal stability and control.
(e) Part 23, § 23.233 Directional stability and control.
(f) Part 23, § 23.493 Braked roll conditions.
(g) Part 23, § 23.731 Wheels.
(h) Part 23, § 23.735 Brakes.
(i) Part 23, § 23.1301 Func tion and installation.
(j) Part 23, § 23.1309 Equipment, systems, and installations.
(k) Part 23, § 23.1529 and Instru ctions for Continued Appendix G to Part 23 Airworthiness.
(l) TSO-C26d “Aircraft Wheels, Brakes and Wheel/Brake Assemblies for Parts 23, 27 and 29 Aircraft with Addendum 1,” October 14, 2004.
NOTE: A description of the certification basis in which an airplane was approved can be obtained from the FAA.