conservative manner. The hull and float are “rigid” conventional amphibian or water-based aircraft structures.
b. Procedures.
(1) The water loads and conditions specified in § 29.519 shall be used. The pressures or load distributions should be appropriate to the design. ANC -3 and §§ 25.523 through 25.535 and Appendix B to FAR Part 25 may be of use.
(2) The water loads and applications of the loads are objective standards. A proposal and early discussions in the life of a project should be used to agree on an appropriate avenue or means of compliance. Tests or analysis supported by tests may be appropriate.
Page D - 66
SUBPART D - DESIGN AND CONSTRUCTION
PERSONNEL AND CARGO ACCOMMODATIONS AC 29.771. § 29.771 (Amendment 29-24) PILOT COMPARTMENT.
a. Explanation.
(1) Volumes have been written on human factors and their contribution to pilot workload and fatigue. This document cannot begin to address the myriad of considerations involved in pilot compartment design. The intent of the rule is simply to ensure that reasonable human factor engineering practices have been followed.
Equipment should be logically grouped within the pilot’s reach and view and be easy to operate. Seats should provide a reasonable level of comfort for the normal anthropometric range of pilots for a typical mission duration. Environmental considerations such as radiation from the sun through overhead windows should be addressed. Heating, cooling, and ventilation systems should be adequate for the range of expected operating conditions.
(2) Each pilot compartment and its equipment should allow the minimum flightcrew to perform their duties without unreasonable concentration or fatigue. If there is a provision/requirement for a second pilot, his station should be equipped with primary flight controls and have easy access to powerplant controls. Duplicate wheel brakes are recommended. Duplication of miscellaneous controls such as idle detent switches, RPM beep functions, nosewheel locks, and parking brakes has not been required. The need for duplicate instruments for the second pilot tends to be a function of cockpit size and panel configuration.
(3) Webster defines appurtenances as “accessory objects or apparatus.” Items such as blowers, fans, and gyros should not have noise or vibration characteristics which could contribute to pilot fatigue or distraction. Instrument panel vibration is specifically addressed in § 29.1321.
(4) Although the rule prohibits in-flight rain or snow leaks that distract the crew or harm the structure, leaks occurring on the ground should also meet these requirements. In extreme cases where an offensive leak could not be stopped, the moisture has been rerouted to a noncritical area. In the context of this rule, “structure” is interpreted to include any part of the pilot compartment to include systems and equipment.
b. Procedures.
(1) Initial evaluation of the pilot compartment should be conducted on the ground. However, the cockpit assessment should be an ongoing effort throughout the flight test program. If a second pilot position is provided/required, the adequacy of Page D - 67
controls and instruments should be evaluated under all normally expected operating conditions. If a second pilot position is not provided/required, any passenger position in the pilot compartment should be evaluated to ensure that a passenger, properly briefed by the flightcrew, can sit comfortably without inadvertent interference with normal control operations. All equipment should be operated during at least one flight of typical mission profile and duration.
(2) Although many pilot compartment rain or snow leaks can be located on the ground by dousing the aircraft with a hose, in-flight leaks often occur in varying intensity and in different locations. Flight in rain should therefore be included during flight test.
AC 29.773. § 29.773 (Amendment 29-56) PILOT COMPARTMENT VIEW.
a. Nonprecipitation Conditions.
(1) Explanation. Amendment 29-56 changed 29.773(a)(2) by adding the option to perform a ground test in lieu of a flight test. Paragraph (a)(1)(iii) below contains guidance to reflect this change.
(i) The procedures paragraph following this explanation discusses one means of demonstrating an adequate field of view.
(ii) Since glare and reflection often differ with the sun’s inclination, consideration should be given to evaluating the cockpit at midday and in early morning or late afternoon. Windshields with embedded wire heating elements should be evaluated for distortion with the system both “ON” and “OFF.”
(iii) If night approval is requested then compliance with 29.773 may be shown by either a ground or flight test. Internal lighting can be evaluated with a ground test. External lighting modifications may require a flight test. If a flight test is conducted, then the lighting system should be evaluated in likely combinations and under expected flight conditions.
(A) Internal lighting evaluations may be accomplished by a ground test with the aircraft in a dark hangar or with external light blocked to create a dark cockpit.
Locations and intensity of instrument panel and control panel light reflections should be assessed to ensure they do not interfere with the pilots’ ability to see outside the aircraft. Figure ac29.773-1 contains guidance on the areas in pilots’ field of vision where reflections should be eliminated. Although a certain amount of equipment reflection (avionics control heads, etc.) In the windshield may be unavoidable, the pilot’s normal field of view should be unobstructed. If reflections are mitigated by modifying the glare shield, then the pilots’ field of view should be revaluated. If a reflection’s effect on the pilots’ ability to see outside the aircraft is uncertain, a night flight test may be required.
(B) External lighting evaluations should be done during night flight tests. Evaluating external lights on the ground may result in unacceptable light entering the cockpit and causing reflections or glare due to reflection off the ground or surrounding structures. Landing and taxi lights should be exercised throughout their adjustment range (if applicable) to check for reflections, particularly in chin windows.
Anticollision and strobe lights should be evaluated to ensure that frequency interaction Page D-68.1
and reflections off the rotor do not result in distractions to the pilot. The effect of cabin lighting on the pilot compartment view should be assessed, particularly on EMS- configured aircraft where the in-flight use of cabin lights may be mandatory
(2) Procedures. The following procedures are one acceptable means of evaluating pilot compartment field of view considering only those objects in the pilot compartment, the windshield, and its support structure in nonprecipitating conditions.
The applicant’s design is not required to meet these guidelines, and each design should be evaluated on its own merits. The area of visibility established in the following paragraphs will provide an acceptable level of visibility for a minimum crew of one (pilot). In the event that a minimum crew of two (pilot and copilot) is required, the Page D-68.2
second pilot should have an area of visibility equivalent to that provided for the pilot but on the opposite side. In this event, the pilot’s area of visibility to the left as shown in figure AC 29.733-1 needs only to comply to 60° left, and the area of visibility for the second pilot needs only to comply to 60° right.
(i) A single point established in accordance with the provisions of this paragraph constitutes the referenced eye position (i.e., a point midway between the two eyes) from which the central axis may be located. The referenced eye position is a reference datum point based on the eye location that permits the specified vision envelope required by figure AC 29.733-1, allows for posture slouch, and is the datum point from which the aircrew station geometry is constructed. The referenced eye position should be located by means of ship’s coordinates that contain station reference number, water line, and butt line for both pilot and copilot, if applicable, and complies with:
(A) The pilot’s seat in a normal operating position from which all controls can be utilized to their full travel, by an average subject, and which should provide for vertical adjustment of the seat of not less than 2.5 inches above and 2.5 inches below this initial vertical position.
(B) The seat back in its most upright position.
(C) The seat cushion depression being that caused by a subject weighing 170 to 200 pounds.
(D) The longitudinal axis of the rotorcraft to be that of “cruise attitude”
(0.9VH or 0.9 VNE whichever is lower).
(E) The point established not beyond 1 inch to the right or left of the longitudinal centerline of the pilot’s seat.
(F) All measurements made from the single point established in accordance with this paragraph.
(ii) A dual lens camera, as photo recorder, should be used in measuring the angles specified in the paragraphs listed below. Other methods, including the use of a goniometer, are acceptable if they produce equivalent areas to those obtained with a dual lens camera. When not using a dual lens camera, compensation should be made for one-half the distance which exists between the eyes, or 1¼ inches. With the referenced eye position located as indicated in paragraph AC 29.733a(2)(i), and utilizing binocular vision and azimuthal movement of the head and eyes about a radius, the center of which is 3 and 5/16 inches behind the referenced position (this point to be known as the central axis), the pilot should have the following minimum areas of vision measured from the appropriate eye position. (See figure AC 29.733-1.)
(A) 20° forward and above the horizon between 0° and 100° left.
Page D - 69
(B) 20° forward and below the horizon between 10° and 100° left.
(C) 20° forward and below the horizon at 10° left increasing to a point 30° forward and below the horizon at 10° right.
(D) 50° forward and below the horizon between 10° right and 135° right.
(E) 20° forward and above the horizon at 0° increasing to a point 40° above the horizon at 80° right and 100° right and then decreasing to a point 20° forward and above the horizon at 135° right.
(iii) Any vertical obstruction which falls within the minimum area of visibility outlined in paragraph AC 29.733a(2)(ii) should be governed by the following:
(A) No vertical obstruction between 20° right and 20° left.
(B) Between 20° right and 135° right, vertical obstruction should not exceed 2.5 inches in width.
(C) Between 20° left and 100° left no vertical obstruction greater than
2.5 inches in width.
(iv) Any horizontal obstruction which falls within the minimum area of visibility outlined in paragraph AC 29.733a(2)(ii) should be governed by the following:
(A) The area 15° forward and above the horizon between 135° right and 40° left decreasing to a point 10° above the horizon at 100° left, and 15° forward and below the horizon between 135° right and 100° left should be free from horizontal obstructions.
(B) The area above and below the horizon which is between the minimum area of vision specified in paragraph AC 29.733a(2)(ii) and paragraph AC 29.733a(2)(iv)(A) is limited to one horizontal obstruction above the horizon, and one below the horizon. These horizontal obstructions should not be greater than 4 inches in width. An overhead window which will provide twice as much additional visibility as was lost due to the obstruction, should be located immediately above any obstruction which is above the horizon. This requirement is in addition to any area of visibility specified by paragraph AC 29.733a(2)(ii) which may be included in the overhead window area.
(C) If the instrument panel obstructs any required area between 10° left and 10° right below 20° forward and below the horizon, a window which affords triple equivalent additional visibility should be located immediately below and between the angles of 20° left and 20° right above 65° below the horizon.
Page D - 70
(v) For steep rejected takeoffs and steep approaches such as used for oil rigs or confined heliports, the visibility should be such that the pilot can see the touchdown pad and sufficient additional area to the side and forward to provide both an accurate approach to the touchdown point as well as a satisfactory degree of depth perception. A 5- inch head movement, by the pilot, forward and/or sideward of the normal position is acceptable in determining compliance.
b. Precipitation Conditions.
(1) Explanation.
(i) Heavy rainfall is defined by the National Weather Service as one resulting in accumulation in excess of 0.03 inches in 6 minutes. On past designs, the windshield wipers required by § 29.1307 have been adequate to ensure satisfactory view at low to medium airspeeds. Airflow over the windshield and/or wipers has normally been sufficient to keep the windshield clear at higher airspeeds. Obscuration of side windows by rainfall should be addressed, particularly for confined area approaches.
(ii) If icing certification is requested, a means must be provided to ensure that a sufficiently large viewing area is kept clear of ice to permit safe operation. As a minimum, a clear area on the windshield should be available, although some configurations could require clear view in other areas, in order to provide an adequate level of safety in certain operations.
(iii) An openable “clear view” window must be provided for the first pilot.
The rule requires that the window be openable in heavy rain at forward speeds to VH and in the worst icing conditions requested for certification. The rule further requires a field of view through this opening which is adequate for safe operation. Although the rule implies that a safe field of view must be provided for airspeeds up to VH, it has not been interpreted as such. In most designs, the only practical location for an openable window is in a side panel or door. Aircraft sideslip limits normally restrict useful view from this window opening at high airspeeds. The intent is to provide the pilot with an adequate view for safe approach and landing in the event that normal windshield clearing systems malfunction.
(2) Procedures. Compliance with the requirements of this rule should be checked by flying the aircraft in the applicable environmental conditions. Although wipers can be partially checked on the ground with a hose, their effectiveness at higher airspeeds should also be verified. Likewise, additional or alternate rain removal systems should be exercised throughout the required airspeed range. The need for windshield wash systems should be assessed, particularly if the aircraft will be used in an offshore salt spray environment. Systems provided to ensure clear view in icing conditions should be evaluated during icing flight tests. The location and effectiveness of the openable window should be evaluated following failure of the rain removal and anti-ice system (if applicable). The view through the window opening should permit safe Page D - 71
operation from hover up to a reasonable approach airspeed. Care should be exercised during flight test to stay within airframe sideslip limits.
Page D - 72
THIS AREA LIMITED TO ONE HORIZONTAL DESTRUCTION (NOT GREATER THAN 4 INCHES IN WIDTH) NO, HORIZONTAL OBSTRUCTIONS TED TO ONE STRUCTION N 4 INCHES IN WIDTH) ND IS CONSIDERED -HAND SEAT) PY RIGH 100° VERTICAL OBSTRUCTIONS LIMITED TO 2.5 INCHES IN WIDTH FIGURE AC 29.773-1 COCKPIT VISIBILITY BETWEEN DASHUNES, THIS AREA 60° ZERD REFERENCE (CENTRAL AXIS) (NOT GREAT (NOTE: PII TOOC 135° 0ª 10° NO VERT. • OBSTRUCTIONS PRET OF YEOR •PILOT VIEW FOR CREWOF ONE 40ª • VERTICAL OBSTRUCTIONS UMITED TO 2.5 INCHES IN WIDTH Page D - 73
AC 29.775. § 29.775 WINDSHIELDS AND WINDOWS.
a. Explanation. Nonsplintering safety glass is specified in windshields and windows containing glass to protect crew and passengers if window fracturing occurs.
In any case, windshields and windows are to be made of transparent materials which will not break into dangerous fragments.
b. Procedures.
(1) Use nonsplintering safety glass in windshield or window applications which contain glass rather than plastic acrylics, polycarbonates, epoxies, etc. The glass selected should meet a specification such as MIL-G-25871, and if new vendors are selected by an airframe manufacturer, test data should be obtained from the vendor to demonstrate the safety glass provided meets an acceptable specification and provides adequate nonsplintering capability.
(2) Windshields and windows should be designed so that either --
(i) They are made of material which will not cause a serious reduction in the field of view by becoming suddenly opaque; or
(ii) Any one panel becoming opaque will not cause a serious reduction in the field of view (reference § 29.773).
(3) In the event of any reasonably probable failure, a transparency heating system must be incapable of raising the temperature of any windshield or window to a point where there would be a danger of fire or structural failure (reference § 29.1309).
AC 29.775A. § 29.775 (Amendment 29-31) WINDSHIELDS AND WINDOWS.
a. Explanation. Amendment 29- 31 changed § 29.775 to allow the use of material other than nonsplintering safety glass; i.e., plastics are allowed. Additionally, whatever material is used should not break into dangerous fragments upon impact.
b. Procedures. The procedures contained in paragraph AC 29.775 apply equally to glass or plastics.
AC 29.775B. § 29.775 (Amendment 29-40) WINDSHIELDS AND WINDOWS.
a. Explanation. Amendment 29- 40 added § 29.631 which requires the rotorcraft be designed to ensure capability of continued safe flight and landing (Category A) or safe landing (Category B) after impact with a 2.2 lb (1.0 kg) bird when the velocity of the rotorcraft (relative to the bird along the flight path of the rotorcraft) is equal to VNE or VH (whichever is lesser) at altitudes up to 8,000 feet.
Page D - 74
b. Procedures. In addition to the procedures outlined above, compliance with § 29.631, should be demonstrated by tests or analysis supported by test evidence that the windshield will withstand, without penetration, the impact with a 2.2 lb (1.0 kg. bird) at VNE or VH (whichever is lesser) at altitudes up to 8,000 feet. See paragraph AC 29.631 (§ 29.631) for additional information.
AC 29.777. § 29.777 COCKPIT CONTROLS.
a. Explanation. This s ection defines the general cockpit control requirements.
Cockpit control location and arrangement, with respect to the pilot’s seat, must be designed to accommodate pilots from 5’2” to 6’0” in height. Pilots within this range should be able to reach and operate all required controls and have sufficient clearance with the structure, panels, etc.
b. Procedures.
(1) The applicant should have a cockpit design report which documents the anthropometric suitability of the cockpit. Subsequent cockpit evaluations of control movement and location should be conducted with adjustable seats and/or controls positioned in a flight position for the subject pilot. Essential controls should be evaluated with the shoulder harness locked in the retracted position. Evaluation pilots should be aware of their individual anthropometric measurements and temper their assessments based on this information. Ideally, a new design should include evaluations by a range of different sized subject pilots. Control considerations f or a second pilot position are the same as for the pilot station. Paragraph AC 29.771 discusses current philosophy concerning duplication of controls.
(2) As background, the following are examples of cockpit control issues which should be avoided:
(i) Collective control blocking the lateral movement of a pilot’s leg, which in turn restricts the left lateral cyclic displacement.
(ii) Seat or seat cushion impeding the aft cyclic movement.
(iii) Inadequate space for large feet equipped with large flight boots.
(iv) Control/seat relationship which requires unusual pilot contortions at extreme control displacements.
(v) Control/seat relationship or control system geometry which will not permit adequate mechanical advantage with unboosted controls or in a boost OFF situation.
(vi) Addition of control panels or equipment to instrument panels or consoles which restrict full control throw.
Page D - 75
(vii) Brake pedal geometry which results in inadvertent brake application upon displacement of the directional controls.
(viii) Controls for accessories or equipment which require a two-handed operation.
(ix) Emergency external cargo release controls which cannot be activated without releasing the primary flight controls.
(x) Essential controls which cannot be actuated during emergency conditions with the shoulder harness locked.
(xi) cutoff position.
Throttle controls which can be inadvertently moved through idle to the
(xii) Switches, buttons, or other controls which can be inadvertently activated during routine cockpit activity including cockpit entry.
(xiii) Failure to account for operation with the pilot wearing bulky winter clothing.
(xiv) Aft cyclic movement limited by the pilot’s body with a fore and aft adjustable seat in the full forward position.
AC 29.779. § 29.779 (Amendment 29-24) MOTION AND EFFECT OF COCKPIT CONTROLS.
a. Explanation. The section standardizes motion and effect of cockpit controls.
While this paragraph specifically addresses primary flight controls, engine power controls, and landing gear controls, it applies to all cockpit controls not addressed in other paragraphs.
b. Procedures.
(1) The cyclic should be mechanized such that movement of the control results in a corresponding sense of aircraft motion in the same axis. While a certain amount of coupling may be present following a pure control input in a given axis, that coupling should not be objectionable to the pilot. Collective pitch control should be mechanized such that an upward movement of the collective results in a corresponding relative motion of the aircraft in the vertical plane. Again, coupling should not be objectionable.
Care should be taken to ensure that the primary pilot perception of collective motion is in the vertical plane. The objective is to clearly differentiate collective motion from that associated with an airplane throttle. The rule is self -explanatory on the subject of engine power controls. A distinction is made between normal landing gear controls an Page D - 76