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(14) Personnel carrying device system (PCDS). The entire attached or suspended system used to carry HEC. This is any HEC carrying configuration such as a suspended (e.g., hoist, cable, harness) HEC system or an attached (e.g., a rigid basket or cage attached to skids) HEC system. (See TSO C167)
(15) Primary Quick-Release Subsystem (PQRS). The primary or "first choice" subsystem used to perform a normal or emergency jettison of external cargo.
(16) Quick-release system (QRS). The entire release system for jettisonable external cargo, (i.e., the sum total of both the primary and backup quick-release subsystems). The QRS consists of all components including the controls, the release devices, and everything in between.
(17) Rescue hook (or hook). A hook that can be rated for both HEC and NHEC. It is typically used in conjunction with a hoist or equivalent system.
(18) Rotorcraft-load combination (RLC ). The combination of a rotorcraft and an external-load, including the external-load attaching means. Rotorcraft-load combinations are designated as Class A, Class B, Class C, and Class D, as follows:
(i) Class A rotorcraft-load combinat ion means one in which the external load cannot move freely, cannot be jettisoned, and does not extend below the landing gear.
(ii) Class B rotorcraft-load combinat ion means one in which the external load is jettisonable and is lifted free of land or water during the rotorcraft operation.
(iii) Class C rotorcraft-load combination means one in which the external load is jettisonable and remains in contact with land or water during the rotorcraft operation.
(iv) Class D rotorcraft-load combinat ion means one in which the externalload is other than a Class A, B, or C and has been specifically approved by the Administrator for that operation (i.e., HEC operations for which the operator is receiving compensation from the person being transported).
(19) Spider: A spider is a system of attaching a lowering cable or rope or a harness to a NHEC (or HEC) RLC to eliminate unwanted flight dynamics during operations. A spider usually has four or more legs (or load paths) that connect to various points of a PCDS to equalize loading and prevent spinning, twisting, or other undesirable flight dynamics.
(20) True jettison capability. The ability to safely release an external load using an approved QRS in 30 seconds or less.
AC 29-2C, Chg 2 4/25/06 Page D - 144 NOTE: In all cases, a PQRS should release the external load in less than 5 seconds.
Many PQRS's will release the external load in milliseconds, once the activation device is triggered. However a manual BQRS such as a set of cable cutters could take as much as 30 seconds to release the external load. The 30 seconds would be measured starting from the time the release command is given and ending when the external load is cut loose.
(21) True payload capability. The ability of an external device or tank to carry a significant payload in addition to its own weight. If little or no payload can be carried, the external device or tank is an external fixture (see definition).
(22) Type inspection authorization (TIA). This is FAA Form 8110-1. It is used for authorizing official ground inspections and flight tests necessary to fulfill the requirements for type certification or supplemental type certification. Order 8110.4, Chapter 2, Section 1, Paragraph 16, states the criteria for TIA issuance.
(23) Winch. A winch is a device t hat can employ a cable and drum or other means to exert a horizontal (i.e., x-rotorcraft axis) pull. However, since a winch can be used to perform a hoist function by use of a 90-degree cable direction change device (such as a pulley or pulley system), a winch system may be considered a hoist.
d. Procedures . The following certification procedures are provided in the most general form. Where there are significant differences between the cargo types, the differences are highlighted.
(1) General Compliance Procedures for § 29.865 : The applicant should clearly identify both the Rotorcraft Load Combinations (RLC) and the applicable cargo types (NHEC or HEC) for which application is being made. The structural loads and operating envelopes for each RLC class and applicable cargo type should be determined and used to formulate the flight manual supplement and basic loads report.
The applicant should show by analysis, test, or both, that the rotorcraft structure, the external load attachment means, and the PCDS, if applicable, meet the specific requirements of §§ 29.865, 133.41, 133.43, 133.45, and the other relevant requirements of Part 29 for the proposed operating envelope.
NOTE: It is possible, if approved, to carry both HEC and NHEC externally, simultaneously as two separate external loads. However, in no case is it intended that the approved Maximum Internal Gross Weight be exceeded for any approved HEC configuration (or combined NHEC and HEC configuration) in normal operations.
Reliability of the external load system. The failure of the external load system, including the PCDS where applicable, and its attachments to the rotorcraft should be shown to be extremely improbable (i.e., 1 x 10-9 failures per flight) for all failure modes that could cause a catastrophic failure, serious injury, or fatality anywhere in the total airborne system. All significant failure modes of lesser consequence should be shown to be
Page D - 145 improbable (i.e., 1 x 10-5 failures per flight). An acceptable method of achieving this goal is to submit and achieve approval of all of the following:
(i) A failure modes and effects analysis (FMEA) showing that all potential failure modes of the airborne system which may result in catastrophic failures, serious injuries, or fatalities are extremely improbable and any less significant failures are improbable.
(ii) A repetitive test of all func tional devices that cycles these devices under critical structural conditions, operational conditions, or a combination of both at least 30 times.
(iii) An environmental qualificat ion review over the proposed operating environment.
AC 29-2C, Chg 2 4/25/06 Page D - 146
Figure AC 29.865B-1 U.S. OPERATIONAL (PART 133) ROTORCRAFT-LOAD COMBINATION
VERSUS APPLICABLE CARGO TYPE DATA AND DEFINITION SUMMARY
Possible RLCs and Cargo Types Category “A” Rating and One Engine Inoperative (OEI) Hover Capability
Notes Direct 2-Way Voice Communications Required See Paragraph d(10) RLC A, HEC No Note 2 No RLC A, NHEC No N/A RLC B, HEC No Note 2 No RLC B, NHEC No N/A RLC C, HEC No Note 2 No RLC C, NHEC No N/A RLC D, HEC Yes, See Paragraph d(12) Note 1, 3, 4 Yes
NOTES:
1. A person(s), being carried or transported for compensation outside the rotorcraft can only be carried as a Class D RLC.
2. A person who is not being carried or transported for compensation, is knowledgeable of the risks involved, and at some point is required to be outside of the rotorcraft in order to fulfill the mission. These persons are considered as RLC Class A, B, or C HEC as appropriate to the operation.
3. The rotorcraft is approved to the Category A engine isolation requirements of Part 29 and have One Engine Inoperative/Out of Ground Effect (OEI/OGE) hover performance capability, for the requested operating and weight envelopes, to be eligible for certification to the Class D RLC. (Reference Paragraph d(12))
4. A Class D RLC operation may be conducted with an external cargo design having a physical configuration that meets the definitions of § 1.1 for RLC Class A, B, or C.
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(2) § 29.865(a) Static Structural Substantiation Procedures: The following static structural substantiation methods should be used.
(i) Critical basic load determination . The critical basic loads and corresponding flight envelope are determined by statically substantiating the gross weight range limits, the corresponding vertical limit load factors (NZW) and safety factors applicable for the type of external load for which the application is being made.
Note: In cases where NHEC or HEC can have more than one shape, center-of-gravity, center-of-lift, or be carried at more than one distance in flight from the rotorcraft attachment, a critical configuration for certification purposes may not be determinable.
If such a critical configuration can be determined, it may be examined for approval as a "worst case" to satisfy a particular certification criterion or several criteria, as appropriate. If such a critical configuration can not be determined, the extreme points of the operational – external load configuration envelope should be examined with consideration given to any other points within the envelope which experience or other rational would indicate should be investigated.
(ii) Vertical Li mit and Ultimate Load Factors. The basic NZW is converted to ultimate load by multiplying the maximum vertical limit load by the appropriate safety factor. (For restricted category approvals, see guidance in paragraph AC 29 MG 5.)
This ultimate load is used to substantiate all existing structure affected by, and all added structure associated with, the load carrying device, its attachments and its cargo.
Casting factors, fitting factors, and other dynamic load factors should be applied where appropriate.
(A) NHEC applications. In most cases, it is acceptable to perform a standard static analysis to show compliance. A vertical limit load factor (NZW) of 2.5 g is typical for heavy gross weight NHEC hauling configurations. (reference § 29.337). This vertical load factor should be applied to the maximum external load for which application is being made, together with a minimum safety factor of 1.5.
(B) HEC applications. If a safety factor 3.0 or more is used, it is acceptable to perform a standard static analysis to show compliance. The safety factor should be applied to the yield strength of the weakest component in the system (QRS, PCDS, and attachment load path). If a safety factor of less than 3.0 is used, both an analysis and a full-scale ultimate load test of relevant parts of the system should be submitted.
Since HEC applications typically involve lower gross weight configurations, a higher vertical limit load factor is required to assure that limit load is not exceeded in service.
The applicant should use either the conservative value of 3.5 g’s or an analytically derived maximum vertical limit load factor for the requested operating envelope. Linear interpolation between the vertical load factors of maximum and minimum design weights
AC 29-2C, Chg 2 4/25/06 Page D - 148 may be used. However, in no case may the vertical limit load factor be less than 2.5 g's for any RLC application for HEC.
For the purpose of structural analysis or test, assume a 223-pound man as the minimum weight of each occupant carried as HEC.
Note: If the HEC is engaged in work tasks that employ devices of significant added weight (heavy backpacks, tools, fire extinguishers, etc.), the total weight of the 223-pound man and equipment should be assumed in the structural analysis or test.
(iii) Critical Structural Case . For applications involving more than one RLC class or cargo type, the structural substantiation is required only for the most critical case. The most critical case should be determined by rational analysis.
(iv) Jettisonable Loads. For the substantiating analyses or tests of all jettisonable RLC external loads, including HEC, the maximum external load should be applied at the maximum angle that can be achieved in service but not less than 30 degrees. The angle should be measured from the sling-load-line to rotorcraft vertical axis (z axis) and may be in any direction that can be achieved in service. The 30-degree angle may be reduced in some or all directions if it is impossible to obtain due to physical constraints or operating limitations. The maximum allowable cable angle should be determined and approved. The angle approval should be based on structural requirements, mechanical interference limits, and flight handling characteristics over the most critical conditions and combinations of conditions in the approved flight envelope.
(v) Hoist system limit load .
Note: In cases where hoist cables or long-line cables are utilized, a new dynamic system is established. Characteristics of the system should be evaluated to assure that either no hazardous failure modes exist or that they are acceptably minimized. For example, the cable or long line may exhibit a natural frequency that could be excited by sources internal to the overall structural system (i.e., the rotorcraft) or by sources external to the system. Another example is the loading effect of the cable acting as a spring between the rotorcraft and the suspended external load.
(A) Determine the basic loads that result in the failure or unspooling of the hoist or its installation, respectively.
NOTE: This determination should be based on static strength and any significant dynamic load magnification factors.
(B) Select the lower of the two values as the ultimate load of the hoist system installation.
Page D - 149 (C) Divide the selected ultimate load by 1.5 to determine the true structural limit load of the system.
(D) Determine the manufacturer's approved (or applicants applied for) "limit design safety factor." Divide this factor into the true structural limit load (from (C) above) to determine the hoist system's working (or placarded) limit load.
(E) Compare the system's deriv ed limit load to the applied for one "g" payload multiplied by the maximum downward vertical load factor (NZWMAX) to determine the critical payload's limit value.
(F) The critical limit payload s hould be equal to or less than the system's derived limit load for the installation to be approvable.
(3) § 29.865(b) and § 29.865(c) Procedures for Quick Release Systems and Cargo Hooks: For jettisonable RLC's of any applicable cargo type, both a primary quick-release system (PQRS) and a back-up quick-release system (BQRS) are required. Features that should be considered are:
(i) The PQRS, BQRS and their load release devices and subsystems (such as electronically actuated guillotines) should be separate (i.e., physically, systematically, and functionally redundant).
(ii) The controls for the PQRS should be installed on one of the pilot's primary controls, or in an equivalently accessible location. The use of an "equivalent accessible location" should be reviewed on a case-by-case basis and used only where equivalent safety is clearly maintained.
(iii) The controls for the BQRS may be less sophisticated than that of the PQRS. For instance, manual cable cutters are acceptable provided they are listed in the flight manual as a required device and have a dedicated, placarded storage location.
(iv) The PQRS should release the external load in less than 5 seconds.
The BQRS should release the external load in less than 30 seconds. This time interval begins the moment an emergency is declared and the ends when the load is released.
(v) Each quick-release device should be designed and located to allow the pilot or a crewmember to accomplish external cargo release without hazardously limiting the ability to control the rotorcraft during emergency situations. The flight manual should reflect the requirement for a crewmember and the related functions.
(vi) Other load release types . In some current configurations, such as those used for high line operations, a load release may be present that is not on the rotorcraft but is on the PCDS itself. Examples are a tension release device that lets out
AC 29-2C, Chg 2 4/25/06 Page D - 150 line under an operationally induced load or a personal rope cutter. These devices are acceptable if:
(A) The off-rotorcraft release is c onsidered a "third release". This type of release is not a substitute for a required release (i.e., PQRS or BQRS);
(B) The release meets other rele vant requirements of § 29.865 and the methods of this AC or equivalent methods; and
(C) The release has no operational or failure modes that would affect continued safe flight and landing under any operations, critical failure modes, conditions, or combination of either.
(vii) Cargo hooks or equivalent devices and their related systems. All cargo hooks or equivalent devices should be approved to acceptable aircraft industry standards. The applicant should present these standards, and any related manufacturer’s certificates of production or qualification as part of the approval package.
(A) General . Cargo hook systems should have the same reliability goals and should be functionally demonstrated under critical loads for NHEC and HEC, as appropriate. All engagement and release modes should be demonstrated. If the hook is used as a quick-release device, then release of critical loads should be demonstrated under conditions that simulate maximum allowable bank angles and speeds and any other critical operating conditions. Demonstration of any re-latching features and any safety or warning devices should also be conducted. Demonstration of actual in-flight emergency quick-release capability may not be necessary if the quick-release capability can be acceptably simulated by other means.
NOTE: Cargo hook manufacturers specify particular shapes, sizes, and cross sections for lifting eyes to assure compatibility with their hook design (e.g., Breeze Eastern Service Bulletin CAB-100-41). Experience has shown that, under certain conditions, a load may inadvertently hang up because of improper geometry at the hook-to-eye interface that will not allow the eye to slide off an open hook as intended.
NOTE : For both NHEC and HEC designs, the phenomena of hook dynamic roll out (inadvertent opening of the hook latch and subsequent release of the load) should be considered to assure that QRS reliability goals are not compromised. This is of particular concern for HEC applications. Hook dynamic roll-out occurs during certain ground handling and flight conditions that may allow the lifting eye to work its way out of the hook.
Hook dynamic roll-out typically occurs when either the RLC's sling or harness is not properly attached to the hook, is blown by down draft, is dragged along the ground or through water; or is otherwise placed into the dangerous hook-to-eye configuration.
Page D - 151 The potential for hook dynamic roll-out can be minimized in design by specifying particular hook-and-eye shape and cross-section combinations. For non-jettisonable RLC's, a pin can be used to lock the hook keeper in place during operations.
NOTE: Some cargo hook systems may employ two or more cargo hooks for safety.
These systems are approvable. However, loss of any load by a single hook should be shown to not result in loss of control of the rotorcraft. In a dual hook system, if the hook itself is the quick-release device (i.e., if a single release point does not exist in the load path between the rotorcraft and the dual hooks), the pilot should have a dual PQRS that includes selectable, co-located individual quick releases that are independent for each hook used. A BQRS should also be present for each hook. For cargo hook systems with more than two hooks, either a single release point should be present in the load path between the rotorcraft and the multiple hook system, or multiple PQRS and BQRS's should be present.
(B) Jettisonable cargo hook systems. For jettisonable applications, each cargo hook-
( 1 ) Should have a sufficient amount of slack in the control cable to permit cargo hook movement without tripping the hook release.
( 2 ) Should be shown to be reliable.
( 3 ) For HEC systems, unless the cargo hook is to be the primary quick-release device, each cargo hook should be designed so that operationally induced loads cannot inadvertently release the load. For example, a simple cargo hook should have a one-way, spring-loaded gate (i.e., "snap hook") that allows load attachment going into the gate but does not allow the gate to open (and subsequently lose the HEC) when an operationally induced load is applied in the opposite direction. For HEC applications, cargo hooks that also serve as a quick-release device should be carefully reviewed to assure they are reliable.
(4) § 29.865(b)(3) Reliability De termination for QRS's and Devices: Quick release systems are required to be reliable. The primary electrical and mechanical failure modes that should be identified and minimized are: (1) load release by any means and (2) loss of continued safe flight and landing capability due to a QRS failure.
However, any failure that could result in catastrophic failure modes, serious injuries, or fatalities should also be identified and shown to be extremely improbable. All other failure modes should be shown to be improbable. The reliability of the system should be demonstrated by completion and approval of all of the following:
(i) A FMEA showing that all potent ial failure mode of the QRS which may result in catastrophic failures, serious injuries, or fatalities are extremely improbable and any less significant failures are improbable.
AC 29-2C, Chg 2 4/25/06 Page D - 152
(ii) A repetitive test of all functi oning devices that affect or comprise the QRS and that tests all critical conditions or combinations of critical conditions at least 10 times each for NHEC and 30 times for HEC, using both the primary and backup QRS subsystems.
(iii) An environmental qualification program that includes consideration of high and low temperatures (typically -40F to +150F), altitudes to 12,000 feet, humidity, salt spray, sand and dust, vibration, shock, rain, fungus, and acceleration. Testing should be conducted in accordance with RTCA/DO-160 or MIL-STD-810 for high and low temperature tests and for vibrations.
(iv) Using the methods of compli ance in other relevant paragraphs of the AC or equivalent methods.
(5) Functional Reliability and Durability Compliance Procedures for Hoist Systems under §§ 29.865(b)(3)(i) and (c)(2): Hoist systems and their installations in the rotorcraft should be designed, approved, and demonstrated as follows:
(i) For established, previously approved hoist unit designs that will be placed in a new rotorcraft installation, certification credit (to Amendment 29-43) for the unit itself can be given based on a successful unit design review (or a manufacturer's statement-of-certification accompanied by an FAA Form 8110-3 with appropriate DER approvals) that shows proper previous approval and that no new design changes have been made that would adversely affect the reliability or function of the unit (i.e., an update of the FMEA). If so approved, then only the hoist installation need be approved during the certification process.
(ii) For new hoist unit designs, the unit should be either approved to a standard aircraft industry specification that has been previously and successfully used to approve hoist units, or an equivalent specification should be developed and used during the certification process.
(iii) It is assumed that only one hoist cycle will typically occur per flight.
This rationale has been used to determine the 10 demonstration cycles for NHEC applications and 30 demonstration cycles for HEC applications. However, if a particular application requires more than one hoist cycle per flight, then the number of demonstration cycles should be increased accordingly.
(iv) The hoist or rescue hook system should be reliable for the phases of flight in which it is operable, unstowed, partially unstowed or in which cargo is carried.
The hoist should be disabled (or an overriding, fail-safe mechanical safety device such as either a flagged removable shear pin or a load-lowering brake should be utilized) to prevent inadvertent load unspooling or release during any extended flight phases and in which hoist operation is not intended. Loss of hoist operational control should also be considered. The reliability of the system should be demonstrated by completion and approval of all of the following:
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(A) A FMEA showing that all potent ial failure mode of the hoist or rescue hook system which may result in catastrophic failures, serious injuries, or fatalities are extremely improbable and any less significant failures are improbable.
(B) Unless a more rational test method is presented and approved, at least 10 repetitive tests of all functional devices that exercises the entire system's functional parameters should be conducted. These repetitive tests may be conducted on the rotorcraft, or by using a bench simulation that accurately replicates the rotorcraft installation.
(C) A hoist unit environmental qualification program that includes consideration of high and low temperatures (typically -40F to +150F), altitudes to 12,000 feet, humidity, salt spray, sand and dust, vibration, shock, rain, fungus, and acceleration. Testing in accordance with RTCA/DO-160 or MIL-STD-810 for high and low temperature tests and for vibrations. The hoist manufacturers should submit a test plan and follow-on test reports to the applicant and FAA following completion of qualification. It is intended that the hoist itself either be prequalified to the EMI and lightning threat levels specified for NHEC or HEC, as applicable for the requested operation, or that it be qualified as part of the entire onboard QRS to these threat levels.
(D) All instructions and documents necessary for continued airworthiness, normal operations, and emergency operations.
(v) Cable attachment . Either the cable should be positively attached to the hoist drum and the attachment should have ultimate load capability, or equivalent means should be provided to minimize the possibility of inadvertent, complete, cable unspooling.
(vi) Cable length and marking . A length of cable nearest the cable's attachment to the hoist drum should be visually marked to indicate to the operator that the cable is near full extension. The length of cable to be marked is a function of the maximum extension speed of the system and the operator's reaction time needed to prevent cable run out. It should be determined during certification demonstration tests.
In no case should the length be less than 3-1/2 drum circumferences.
(vii) Cable stops . Means should be present to automatically stop cable movement quickly when the system's extension and retraction operational limits are reached.
(viii) Hoist system load-speed combination ground tests . The load versus speed combinations of the hoist should be demonstrated on the ground (either using an accurate engineering mock-up or a rotorcraft) by showing repeatability of the no loadspeed combination, the 50 percent load-speed combination, the 75 percent load-speed combination and the 100 percent (i.e., system rated limit) load-speed combination. If
AC 29-2C, Chg 2 4/25/06 Page D - 154 more than one operational speed range exists, the preceding tests should be performed at either all speeds, or at the most critical speed.
(A) At least 1/10 of the demons tration cycles (see definition) should include the maximum aft angular displacement of the load from the drum, applied for under § 29.865(a).
(B) A minimum of six consecutive, complete operation cycles should be conducted at the system's 100 percent (i.e., system limit rated) load-speed combination.
(C) In addition, the demonstration should cover all normal and emergency modes of intended operation and should include operation of all control devices such as limit switches, braking devices, and overload sensors in the system.
(D) All quick disconnect devices and cable cutters should be demonstrated at 0 percent, 25 percent, 50 percent, 75 percent, and 100 percent of system limit load or at the most critical percent.
NOTE: Some hoist designs have built-in cable tensioning devices that function at the no load-speed combination, as well as at other load-speed combinations. This device should work during the no load-speed and other load-speed cable-cutting demonstrations.
(E) All electrical and mechanical systems and load release devices for any jettisonable NHEC or HEC RLC should be shown to be reliable by both analysis and by testing.
(F) Any devices or methods used to increase the mechanical advantage of the hoist should also be demonstrated.
(G) During a portion of each dem onstration cycle, the hoist should be operated from each station from which it can be controlled.
NOTE: A reasonable amount of starting and stopping during demonstration cycles is acceptable.
(ix) Hoist system continued airworthiness . The design life of the hoist system and any limited life components should be clearly identified, and the Airworthiness Limitations Section of the maintenance manual should include these requirements. For STC's, a maintenance manual supplement should be provided that includes these requirements.
NOTE: Design lives of hoist and cable systems are typically between 5,000 to 8,000 cycles. Some hoist systems have usage time meters installed. Others may have cycle counters installed. Cycle counters should be considered for HEC operations and high load or other operations that may cause low-cycle fatigue failures.