(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.
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(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.
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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.
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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.
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(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
emergency controls. Emergency controls may operate in a sense which might not correspond to the direction of resultant gear motion.
(2) The recommended operating convention and “switchology” for miscellaneous controls is:
(i) Up/forward = on/increase.
(ii) Down/aft = off/decrease.
(iii) Variable rotary controls should move clockwise from the OFF position, through an increasing range, to the full ON position. For some variable intensity controls such as instrument lighting, the desired minimum setting may not be completely off. Pushbuttons not giving an obvious indication of mechanical position should be configured such that the flightcrew has a clear indication of switch actuation under both day and night (if applicable) conditions. Failure of the indication should be shown to be free of hazards.
(3) Slew or “beep” switches associated with flight control system applications warrant special attention. The recommended conventions for control -mounted single, or multifunction, two or four-way “beep” switches are:
(i) Cyclic.
Switch Direction Flight Control System /Autopilot Configuration Aircraft Response Forward/up basic trim nose down airspeed/groundspeed mode selected increased airspeed forward speed reference vertical speed mode selected (without airspeed mode engaged) increased rate of descent/decreased rate of climb hover mode selected increased ground-speed or forward acceleration reference Left basic trim left wing down heading mode selected slew heading reference left hover mode selected increased ground-speed or acceleration reference to left Page D - 77
(ii) Collective (assumes switch is mounted on top of grip).
Switch Direction Flight Control System /Autopilot Configuration Aircraft Response Forward control position hold down collective vertical speed mode selected increased rate of descent/decreased rate of climb hover mode selected decreased hover height reference Left control position hold increase left pedal hover mode selected slew heading reference left
(iii) Opinions are divided concerning the preferred convention for forward and rearward motion of slew switches mounted atop the collective grip. Part of the reason appears to stem from the fact that such a switch is never used in a purely control position trim capacity. The switch has normally remained nonfunctional until a vertical autopilot mode is selected. At that point, the switch is viewed by one pilot/engineer contingent as either an autopilot reference slew function or a power increase/decrease switch, which should follow the “forward equals increase” convention. The other group views the switch as a form of control position trim and finds the “forward equals down collective” convention to be more consistent with the sensing used for the cyclic beep switches. An obvious solution is to mount collective/vertical axis switches in a vertical orientation on the grip. Barring that alternative, viable arguments can be made for either philosophy. The recommended convention was selected following a survey of manufacturers and test pilots.
AC 29.783. § 29.783 (Amendment 29-20) DOORS.
a. Explanation. This regulation requires at least one door for all closed cabin rotorcraft. Standards for all doors and airstair doors are included. To assure that the doors provide normal entry and egress without causing or contributing to hazardous conditions, even after a minor crash, the following requirements are imposed:
(1) Passenger doors may not be located with respect to any rotor to endanger persons using the doors as instructed.
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(2) Means are required for locking crew and external passenger doors to prevent their opening in flight due--
(i) To inadvertent operation; or
(ii) To mechanical failure.
(3) External doors are required to be openable from the inside or outside by simple and obvious means.
(4) Reasonable provisions to prevent jamming of external doors are required as specified and to assure that an “airstair door” is useable.
(5) The following visual indications of external doors being closed and locked are required:
(i) Direct visual inspection means by crewmembers of the locking mechanism of all external doors.
(ii) Visual means to signal to crewmembers “when normally used external doors are closed and fully locked.”
(6) For certain outward opening doors, an auxiliary safety latching device is required “to prevent the door from opening when the primary latching mechanism fails.”
Suitable operating procedures to prevent this device from being used during takeoff and landing are required if the door cannot be opened from outside the rotorcraft (reference § 29.783(c)) with the device in place.
(7) If the door is a sliding door and intended to be opened and closed in flight, the sliding mechanism should positively attach the door to the airframe (e.g., sliding hinge) to minimize the likelihood of the door departing the aircraft in flight. Appropriate flight limitations should also be established to minimize any hazard while operating the door.
b. Procedures.
(1) Passenger doors should be located as far as possible from the auxiliary rotors. The doors may be hinged and door open stops may be provided to separate entering and egressing passengers from the auxiliary rotor blades. If necessary for the design, “appropriate instructions” should be provided for all passenger doors concerning entering and leaving the rotorcraft and safe use of each door relative to all rotors.
These instructions should be obvious to a passenger using the door, contain large enough letters to be readily legible, and use letters or background colors associated with danger (i.e. orange or red).
(2) Means to prevent the opening of doors in flight.
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AC 29-2C, Chg 3 9/30/2008
(i) Means to prevent the opening of doors in flight due to inadvertent operation may be provided by recessing door handles to prevent their inadvertent operation by the normal movement of passengers about the cabin. If recessing the door handle is impractical, a cover may be provided which will prevent inadvertent operation of the handle, but the cover should be of such design that it does not obscure the door handle or its operating instructions. It must not unduly interfere with deliberate operation of the door handle by passenger or crew. Transparent or nonsolid covers, easily displaced by deliberate actions, have been used to prevent inadvertent door handle operation. Some rotorcraft designs meet this requirement by requiring that passengers wear their seat belts at all times during flight. This design requires that the “fasten seat belt” sign be on at all times the rotorcraft is in flight (for practical purposes, the “fasten seat belt” light is generally designed to be on when power is applied to the rotorcraft).
(ii) Means to prevent inadvertent door opening in flight due to “mechanical failure” is most efficiently provided by multiple door latches and multiple load path door locking mechanisms so that the door will remain locked after a single failure. Care should be taken in the design of multiple load path latches and mechanisms to assure independence of all failures and to consider the effort of deflections after failures (if a failure allows deflections into the airstream sufficient to increase aerodynamic loads, the increase in loads should be accounted for; if a failure allows significant movement of latching components, the deflections should be accurately accounted for to assure that disengagement of nonfailed latches does not occur).
(3) The means to open normally used external doors is required to be simple (such as a rotating handle) and to be accessible from the inside or the outside. To prevent the inadvertent use of emergency exits (separate from normal entry doors) for routine entry and exit with the resulting “wear and tear,” the normally used doors for entry and exits should be equipped with operating handles and instructions distinctly different from those of the emergency exits. Obviously, the above does not apply to normally used exits which are also the primary (or only) emergency exits.
(4) Reasonable provisions to prevent jamming of external doors include the following:
(i) Design features of doors which are insensitive to large fuselage deflections for door operation.
(ii) Provision of clearance between door and door frame latching devices sufficient to allow some relative deflection between the door and door frame and still allow door operation. The relative deflections may be determined by static test or by an analysis approved by the FAA/AUTHORITY.
(iii) Sliding doors are frequently used in transport rotorcraft for versatility and utility reasons. If sliding doors are used, one of the following features of design may be required to assure that the requirements of § 29.783(d) are met:
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(A) The sliding door(s) must be provided with jettison features which allow release of the door(s) from the tracks (to preclude jamming). The emergency release is generally separate and distinct from the normal door handle.
(B) Separate emergency exits of appropriate size and number may be installed in the sliding door(s).
(C) Separate emergency exits of appropriate size and number may be installed in addition to the sliding door(s).
(iv) Whether or not the sliding door is qualified as an emergency exit, it must meet the remaining door design standards.
(5) Direct visual inspection means by crewmembers of the locking mechanism of external doors may provide for visual observation of the door frame and the latching components for engagement or for visual observation of “flag” areas of the locking mechanism. If “flag” areas are used (such as tabs or shoulders which protrude into the crewmember’s line of sight when the latches are engaged (locked)), care should be taken to assure that the tab is permanently affixed (or an integral part) to the locking mechanism; and it should not give erroneous readings to the crewmembers under any foreseeable operation or failure of the latching mechanism. “Visual means to signal” to crewmembers “when normally used external doors are closed and fully locked” may be provided by annunciator panel lights or equivalent means. The visual indicating system may consist of an indicator for each individual door, or a system connecting all doors in series. If the latter system is used, it need not necessarily show which door is not fully locked. It is not necessary that more than one crewmember be able to ascertain by a visual signal that all external doors normally used by the crew in supplying the rotorcraft, or in loading and unloading passengers and cargo, are fully closed and locked. The visual signal should be located so that it may easily be seen by the appropriate crewmember from his station.
(6) For § 29.783(f), the auxiliary safety latching device to “prevent the door from opening when the primary latching mechanism fails” can be provided by the same multiple load path features which meet the § 29.783(c) requirement for prevention of door opening in flight after a “mechanical failure.” If a completely separate “auxiliary safety latching device” is used, it should allow the door to be opened from the inside, or outside, when in place. If the device must be removed to allow use of the door, “suitable operating procedures” (i.e., placards and RFM instructions) will be required for removal of the device during takeoff and landing.
(7) Additional standards for “airstair doors” were added by Amendment 29-20.
(i) An analysis or test may be used to prove compliance with deformation standards in § 29.783(g)(1).
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