ground run and is used to determine IAS values for various V1 and VR speeds. See Appendix 9 for definitions, test procedures, and sample data reductions.
g. Other Methods. Other methods of airspeed calibration are described in NASA Reference Publication 1046, "Measurement of Aircraft Speed and Altitude," by W. Gracey, May 1980.
Refer to appendix 9 for GPS method.
304. SECTION 23.1325 STATIC PRESSURE SYSTEM.
a. Definitions. Paragraph 302 defines several of the terms associated with the pitot-static systems. Others may need further explanation.
(1) Altimeter. An altimeter is a pressure gauge that measures the difference between a sea level barometer pressure set on the instrument and static pressure, and indicates in units of feet.
(2) Static Error (error in pressure altitude). The error that results from the difference between the actual ambient pressure and the static pressure measured at the airplane static pressure source is called static error. Static error causes the altimeter to indicate an altitude that is different than actual altitude. It may also affect the errors in the airspeed indicating system.
b. Static System Calibration. The static system is calibrated to determine compliance with the requirements of § 23.1325. The static system may be calibrated by utilizing a trailing bomb, cone, or tower fly-by method. Alternately, for properly designed pitot systems, the pitot has minimal affect on the airspeed position error (dVc), as determined for § 23.1323. For these systems, static error (dh) may be calculated by the following equation:
() .ft,V5.661V2.01dV08865.0dh C
5.22 CC ⎥⎦⎤⎢⎣⎡ σ⎥⎥⎦⎤⎢⎢⎣⎡ ⎥⎦⎤⎢⎣⎡+=
where Vc = calibrated airspeed, knots σ = ambient air density ratio dV c = airspeed position error
c. Test Methods. The methods specified for calibration of the airspeed indicating systems, including test conditions and procedures, apply equally for determining static error and error in indicated pressure altitude, and are usually determined from the same tests and data.
d. Tower Fly-by. The tower fly-by method is one of the methods that results in a direct determination of static error in indicated pressure altitude without the need for calculating from airspeed position error.
e. Procedures and Test Conditions for Tower Fly-by.
(1) Air Quality. Smooth, stable air is needed for determining the error in pressure altitude.
(2) Weight and C.G. Same as for calibrations of the airspeed indicating system.
(3) Speed Range. The calibration should range from 1.3 VSO to 1.8 VS1. Higher speeds up to VMO or VNE are usually investigated so that errors can be included in the AFM for a full range of airspeeds.
(4) Test Procedures.
(i) Stabilize the airplane in level flight at a height that is level with the cab of a tower, or along a runway while maintaining a constant height of 50 to 100 feet by use of a radio altimeter. A ground observer should be stationed in the tower, or on the runway with an altimeter of known instrument error. Pressure altitude is recorded on the ground and in the airplane at the instant the airplane passes the ground observer.
(ii) Repeat step (i) at various airspeeds in increments sufficient to cover the required range and at each required flap setting.
(5) Data Acquisition. Data to be recorded at each test point:
(i) Airplane IAS;
(ii) Airplane indicated pressure altitude;
(iii) Ground observer indicated pressure altitude;
(iv) Radar altimeter indication (if flown along a runway);
(v) Wing flap position; and
(vi) Landing gear position.
(6) Data Reduction.
(i) Method.
(A) Correct indicated pressure altitude values for instrument error associated with each instrument.
(B) To obtain test pressure altitude, adjust the ground observed pressure altitude by the height read from the radar altimeter. No adjustment is required if the airplane was essentially the same level as the ground operator (tower cab). Static errors may be adjusted from test pressure altitude to sea level by the following:
dh (S.L.) = [ ][ ])TEST()TEST(dh σ
Where:
dh (TEST) = Difference in test pressure altitude and airplane pressure altitude with associated instrument errors removed.
σ (TEST) = ambient air density ratio.
(i) Plotting. Static error at sea level (dh (S.L.) ) should be plotted vs. test calibrated airspeeds.
(7) Required Accuracy. Section 23.1325(e) requires that the error in pressure altitude at sea level (with instrument error removed) must fall within a band of ±30 feet at 100 knots or less, with linear variation of ±30 feet per 100 knots at higher speeds. These limits apply for all flap settings and airspeeds from 1.3 VSO up to 1.8 VS1. For commuter category airplanes, the altimeter system calibration should be shown in the AFM.
305. SECTION 23.1326 PITOT HEAT INDICATION SYSTEMS. (RESERVED)
306. SECTION 23.1327 MAGNETIC DIRECTION INDICATOR. (RESERVED)
307. SECTION 23.1329 AUTOMATIC PILOT SYSTEM.
This subject is covered in AC 23-17.
308. SECTION 23.1331 INSTRUMENTS USING A POWER SUPPLY. (RESERVED)
309. SECTION 23.1335 FLIGHT DIRECTOR SYSTEMS. (RESERVED)
310. SECTION 23.1337 POWERPLANT INSTRUMENTS.
a. Explanation.
(1) Fuel Quantity Indicator. The indicator should be legible and easily read without excessive head movement. The calibration units and the scale graduations should be readily apparent. Units should be consistent with AFM procedures and performance data.
(2) Auxiliary Tanks. A fuel quantity indicator is not required for a small auxiliary tank that is used only to transfer fuel to another tank if the relative size of the tank, the rate of fuel flow, and operating instructions are adequate. The requirement for a separate quantity indicator should be determined by analysis of design data prior to flight test. The relative size of the tanks, intended use of the auxiliary tanks, complexity of the fuel system, and so forth, should be considered in determining the need for a fuel quantity indicator. If an indicator is not installed, flight manual procedures should ensure that once transfer of fuel is started, all fuel from the selected auxiliary tank can be transferred to the main tank without overflow or overpressure.
b. Procedures. Evaluate indicators for clarity and legibility. Review AFM for consistency of units and validity of procedures.
311.-318. RESERVED.
Section 3. ELECTRICAL SYSTEMS AND EQUIPMENT
319. SECTION 23.1351 GENERAL. (RESERVED)
320. SECTION 23.1353 STORAGE BATTERY DESIGN AND INSTALLATION.
a. Explanation. When ascertaining that the installed airplane battery capacity is adequate for compliance with § 23.1353(h), account should be taken of any services or equipment essential for the continued safe flight and landing of the particular airplane in accordance with the approved emergency procedures and in any approved conditions of operation. Account should also be taken of those services that cannot readily be shed. In order to ensure that services will function adequately for the prescribed period, the duration of battery supply should normally be based on a battery capacity of 72 percent of the nameplate rated capacity at the one hour rate. This figure takes into consideration the battery state of charge, the minimum capacity permitted during service life and the battery efficiency and is based on a battery capacity of 80 percent of the nameplate rated, at the one hour rate, and a 90 percent state of charge. Recognition time may depend on the kind of warning systems.
Section 23.1353 (h) is as follows:
In the event of a complete loss of the primary electrical power generating system, the battery must be capable of providing at least 30 minutes of electrical power to those loads that are essential to continued safe flight and landing. The 30-minute time period includes the time needed for the pilots to recognize the loss of generated power and take appropriate load shedding action.
The airplane characteristics and all systems needed for continued safe flight and landing for all intended operations need to be considered. Assuming operations will be under Part 135 IFR conditions; and only addressing the specific requirements under Part 91 and 135 the current type certificate application for Part 23, amendment 23-53, single-pilot, day/night/VFR/IFR, with approval for flight-into-known-icing conditions.
The 30-minute of electrical power should include the following equipment/instruments if they require electrical power:
• One airspeed and altimeter, with a heated pitot tube and heated static pressure source if needed to comply with section 23.1325.
• Instrument light for the magnetic compass.
• One navigational equipment appropriate to the ground facilities to be used.
• One communications systems.
• One gyroscopic pitch and bank indicator.
• One clock.
• Any powerplant parameter necessary for continued safe flight and landing or for engine restart
• Electronic Engine Controls, if installed.
b. Procedures. None.
321. SECTION 23.1357 CIRCUIT PROTECTIVE DEVICES. (RESERVED)
322. SECTION 23.1361 MASTER SWITCH ARRANGEMENT.
This subpart requires a master switch arrangement to be installed. Confirm that the master switch arrangement is prominently located and marked. The master switch, in accordance with § 23.1355(e)(2), is considered to be an emergency control and should be colored red.
323. SECTION 23.1367 SWITCHES. (RESERVED)
324.-328. RESERVED.
Section 4. LIGHTS
329. SECTION 23.1381 INSTRUMENT LIGHTS. (RESERVED)
330. SECTION 23.1383 LANDING LIGHTS. (RESERVED)
331.-335. RESERVED.
Section 5. SAFETY EQUIPMENT
336. SECTION 23.1411 GENERAL. (RESERVED)
337. SECTION 23.1415 DITCHING EQUIPMENT. (RESERVED)
338. SECTION 23.1416 PNEUMATIC DEICER BOOT SYSTEM. See AC 23-17.
339. SECTION 23.1419 ICE PROTECTION. See AC 23-17 and AC 23.143-1.
340.-349. RESERVED.
Section 6. MISCELLANEOUS EQUIPMENT
350. SECTION 23.1431 ELECTRONIC EQUIPMENT.
Section 23.1431(e) requires that the flight crewmembers will receive all aural warnings when any headset is being used. For those installations where not all warnings are provided through the radio/audio equipment, the manufacturers should demonstrate that all warnings will be heard and recognized when noise canceling headsets are used.
351. SECTION 23.1435 HYDRAULIC SYSTEMS. (RESERVED)
352. SECTION 23.1441 OXYGEN EQUIPMENT AND SUPPLY. (RESERVED)
353. SECTION 23.1447 EQUIPMENT STANDARDS FOR OXYGEN DISPENSING UNITS.
(RESERVED)
354. SECTION 23.1449 MEANS FOR DETERMINING USE OF OXYGEN. (RESERVED)
355. SECTION 23.1457 COCKPIT VOICE RECORDERS. (RESERVED)
356. SECTION 23.1459 FLIGHT RECORDERS. (RESERVED)
357.-364. RESERVED.
CHAPTER 6. OPERATING LIMITATIONS AND INFORMATION Section 1. GENERAL
365. SECTION 23.1501 GENERAL.
a. Explanation.
(1) Flight Crew Information. This section establishes the obligation to inform the flight crew of the airplane's limitations and other information necessary for the safe operation of the airplane. The information is presented in the form of placards, markings, and an approved AFM. Appendix 4 can be used to assist in determining which methods of presentation are required.
(2) Minimum Limitations. Sections 23.1505 through 23.1527 prescribe the minimum limitations to be determined. Additional limitations may be required.
(3) Information Presentation. Sections 23.1541 through 23.1589 prescribe how the information should be made available to the flight crew.
b. Procedures. None.
366. SECTION 23.1505 AIRSPEED LIMITATIONS.
a. Explanation. This section establishes the operational speed limitations for safe margins below design speeds. For reciprocating engine-powered airplanes there is an option. They may either establish a never-exceed speed (VNE) and a maximum structural cruising speed (VNO) or they may be tested in accordance with § 23.335(b)(4), in which case the airplane is operated under a maximum operating speed concept (VMO/MMO). For turbine-powered airplanes, a VMO/MMO should be established. Tests associated with establishing these speeds are discussed under § 23.253, High Speed Characteristics.
b. Procedures. None.
367. SECTION 23.1507 MANEUVERING SPEED.
This regulation is self-explanatory.
368. SECTION 23.1511 FLAP EXTENDED SPEED.
This regulation is self-explanatory.
369. SECTION 23.1513 MINIMUM CONTROL SPEED.
This regulation is self-explanatory.
370. SECTION 23.1519 WEIGHT AND CENTER OF GRAVITY.
This regulation is self-explanatory.
371. SECTION 23.1521 POWERPLANT LIMITATIONS. (RESERVED)
372. SECTION 23.1523 MINIMUM FLIGHT CREW. (RESERVED)
373. SECTION 23.1523 MINIMUM FLIGHT CREW.
a. Discussion. The following should be considered in determining minimum flight crew:
(1) Basic Workload Functions. The following basic workload functions should be considered:
(i) Flight path control;
(ii) Collision avoidance;
(iii) Navigation;
(iv) Communications;
(v) Operation and monitoring of aircraft controls;
(vi) Command decisions; and
(vii) Accessibility and ease of operation of necessary controls.
(2) Workload Factors. The following workload factors are considered significant when analyzing and demonstrating workload for minimum flight crew determination:
(i) The impact of basic airplane flight characteristics on stability and ease of flight path control. Some factors such as trimmability, coupling, response to turbulence, damping characteristics, control breakout forces and control force gradients should be considered in assessing suitability of flight path control. The essential elements are the physical effort, mental effort and time required to track and analyze flight path control features, and the interaction with other workload functions.
(ii) The accessibility, ease, and simplicity of operation of all necessary flight, power, and equipment controls, including emergency fuel shutoff valves, electrical controls, electronic controls, pressurization system controls, and engine controls.
(iii) The accessibility and conspicuity of all necessary instruments and failure warning devices such as fire warning, electrical system malfunction, and other failure or caution indicators. The extent to which such instruments or devices direct the proper corrective action is also considered.
(iv) The complexity and difficulty of operation of the fuel system, with particular consideration given to the required fuel management schedule necessitated by c.g., structural, or other airworthiness considerations. Additionally, the ability of each engine to operate continuously from a single tank or source that is automatically replenished from other tanks if the total fuel supply is stored in more than one tank.
(v) The degree and duration of concentrated mental and physical effort involved in normal operation and in diagnosing and coping with malfunctions and emergencies, 147
including accomplishment of checklist, and location and accessibility of switches and valves.
(vi) The extent of required monitoring of the fuel, hydraulic, pressurization, electrical, electronic, de-icing, and other systems while en route. Also, recording of engine readings, and so forth.
(vii) The degree of automation provided in the event of a failure or malfunction in any of the aircraft systems. Such automation should ensure continuous operation of the system by providing automatic crossover or isolation of difficulties and minimize the need for flight crew action.
(viii) The communications and navigation workload.
(ix) The possibility of increased workload associated with any emergency that may lead to other emergencies.
(x) Passenger problems.
(3) Kinds of Operation Authorized. During minimum crew determination, consideration should be given to the kinds of operation authorized under § 23.1525. Inoperative equipment could result in added workload that would affect minimum crew. It may be determined that, due to minimum crew workload considerations, certain equipment must be operative for a specific kind of operation.
b. Acceptable Techniques.
(1) General.
(i) A systematic evaluation and test plan should be developed for any new or modified airplane. The methods for showing compliance should emphasize the use of acceptable analytical and flight test techniques. The crew complement should be studied through a logical process of estimating, measuring, and then demonstrating the workload imposed by a particular flight deck design.
(ii) The analytical measurements should be conducted by the manufacturer early in the airplane design process. The analytical process that a given manufacturer uses for determining crew workload may vary depending on flight deck configuration, availability of a suitable reference, original design or modification, and so forth.
(2) Analytical Approach.
(i) A basis for deciding that a new design is acceptable is a comparison of a new design with a previous design proven in operational service. By making specific evaluations and comparing new designs to a known baseline, it is possible to proceed with confidence that the changes incorporated in the new designs accomplish the intended result. When the new flight deck is considered, certain components may be proposed as replacements for conventional items, and some degree of rearrangement may be contemplated. New avionics systems may need to be fitted into existing panels, and newly automated systems may replace current indicators and controls. As a result of these evolutionary 148
characteristics of the flight deck design process, there is frequently a reference flight deck design, which is usually a conventional airplane that has been through the test of operational usage. If the new design represents an evolution, improvement attempt, or other deviation from this reference flight deck, the potential exists to make direct comparisons. While the available workload measurement techniques do not provide the capacity to place precise numbers on all the relevant design features in reference to error or accident potential, these techniques do provide a means for comparing the new proposal to a known quantity. Service experience should be researched to assure that any existing problems are understood and not perpetuated.
(ii) After studying a new component or arrangement and exercising it in practical flight scenarios, a test pilot may not be able to grade that design in finer workload units than "better" or "worse than." If the pilot can say with reliability and confidence that it is or is not easier to see a display or to use an augmented control system than to use a functionally similar unit of a reference design, then these "better" or "worse than" judgments—if corroborated by a reasonable sample of qualified pilots over various assumed flight regimes— provide substantial evidence that workload is or is not reduced by the innovation.
(A) If an early subjective analysis by FAA flight test personnel shows that workload levels may be substantially increased, a more in-depth evaluation of flight testing may be required to prove acceptability of the increased workload. In this case, there should be available workload latitude in the basic flight deck design to accommodate the increase.
(B) If the new design represents a "revolutionary" change in level of automation or pilot duties, analytic comparison to a reference design may have lessened value.
Without a firm data base on the time required to accomplish both normally required and contingency duties, more complete and realistic simulation and flight testing will be required.
(3) Testing.
(i) In the case of the minimum crew determination, the final decision is reserved until the airplane has been flown by a panel of experienced pilots, trained and qualified in the airplane. The training should be essentially that required for a type rating. When the applicant seeks single pilot approval, the evaluation pilots should be experienced and proficient in single pilot operations. Section 23.1523 contains the criteria for determining the minimum flight crew. These criteria contain basic workload functions and workload factors.
(ii) The workload factors are those factors that should be considered when evaluating the basic workload functions. It is important to keep in mind the key terms basic workload and minimum cues when analyzing and demonstrating workload. For example, an evaluation of communications workload should include the basic workload required to properly operate the airplane in the environment for which approval is sought. The goal of evaluating crew complement during realistic operating conditions is important to keep in mind if a consistent evaluation of minimum flight crew is to be accomplished.
(iii) The flight test program for showing compliance should be proposed by the applicant and should be structured to address the following factors:
(A) Route. The routes should be constructed to simulate a typical area that is likely to provide some adverse weather and Instrument Meteorological Conditions (IMC), as well as a representative mix of navigation aids and Air Traffic Control (ATC) services.
(B) Weather. The airplane should be test flown in a geographical area that is likely to provide some adverse weather, such as turbulence and IMC conditions, during both day and night operations.
(C) Crew Work Schedule. The crew should be assigned to a daily working schedule representative of the type of operations intended, including attention to passenger cabin potential problems. The program should include the duration of the working day and the maximum expected number of departures and arrivals. Specific tests for crew fatigue are not required.
(D) Minimum Equipment Test. Preplanned dispatch-inoperative items that could result in added workload should be incorporated in the flight test program. Critical items and reasonable combinations of inoperative items should be considered in dispatching the airplane.
(E) Traffic Density. The airplane should be operated on routes that would adequately sample high density areas, but should also include precision and nonprecision approaches, holdings, missed approaches, and diversion to alternate airports.
(F) System Failures. Consequences of changes from normal to failed modes of operation should be included in the program. Both primary and secondary systems should be considered.
(G) Emergency Procedures. A sampling of various emergencies should be established in the test program to show their effect on the crew workload.
NOTE: Prior to selecting the system failure and emergency procedures that will be evaluated in the flight test program, analytical studies of proposed abnormal and emergency procedures should be conducted. The acceptability of all procedures should be verified and the crew workload distribution during the execution of these procedures understood to assure selection of appropriate failure cases.
(4) Determining Compliance.
(i) The type certification team that serves as pilots and observers should be equipped with flight cards or other means that allow for record keeping of comments addressing the basic workload functions. These records should be accumulated for each flight or series of flights in a given day. In addition, the certification team should record the accuracy of using operational checklists. For the purposes of this data gathering, the airplane should be configured to allow the team evaluators to observe all crew activities and hear all communications both externally and internally.
(ii) Each subparagraph of paragraph 373a summarizes an observation of pilot performance that is to be made. Judgment by the certification team members should be that each of these tasks has been accomplished within reasonable pre-established workload standards during the test flights. A holistic pilot evaluation rationale is needed in view of the wide variety of possible designs and crew configurations that makes it unfeasible to assume that ratings are made against every alternative and against some optimum choices. The regulatory criteria for determining minimum flight crew do not adapt well to finely-scaled measurements. Specific feature and activity pass-fail judgments should be made. Pass means that the airplane meets the minimum requirements.
374. SECTION 23.1524 MAXIMUM PASSENGER SEATING CONFIGURATION.
This regulation is self-explanatory.
375. SECTION 23.1525 KINDS OF OPERATION.
a. Explanation.
(1) Required Equipment. See discussion under § 23.1583(h), paragraph 411 of this AC, concerning required equipment for each certificated kind of operation.
(2) Icing. With respect to operations in icing conditions, it is important that operating limitations be established in order to specify the required equipment in § 23.1583(h) and to provide the proper placard required by § 23.1559 (flight in icing approved or prohibited).
376. SECTION 23.1527 MAXIMUM OPERATING ALTITUDE.
a. Explanation.
(1) Safe Operation. Section 23.1527 requires the establishment of a maximum operating altitude for all turbine, turbo-supercharged, and pressurized airplanes based on operation limited by flight, structural, powerplant, functional or equipment characteristics. Section
23.1501(a) requires limitations necessary for safe operation be established. Thus, if an unsafe condition occurs beyond a particular operating altitude for any airplane, that altitude should be established as a limitation under § 23.1501(a).
(2) Windshields and Windows. As stated in § 23.1527(a), pressurized airplanes are limited to 25,000 feet unless the windshield/window provisions of § 23.775 are met.
(3) Factors. The maximum operating altitude listed in the AFM should be predicated on one of the following:
(i) The maximum altitude evaluated;
(ii) The restrictions, as a result of either unsatisfactory structures, propulsion, systems, or flight characteristics, or all of these; or
(iii) Consideration of § 23.775 for pressurized airplanes.