Helicopter Performance Performance Class 1 Jim Lyons
What is Performance Class 1 Content of Presentation Elements of a Category A Take-off Procedure (CS/FAR 29) PC1 Take-off Requirements PC1 En-Route Requirements PC1 Landing Requirements Category A Extensions HEMS Seminar 15
Operational - Classification Performance Class 1 operations are those with performance such that, in the event of failure of the critical power unit, the helicopter is able to land within the rejected take-off distance available or safely continue the flight to an appropriate landing area, depending on when the failure occur. HEMS Seminar 16
Category A The Definition Category A with respect to rotorcraft, means a multi-engined rotorcraft designed with engine and system isolation features specified in CS 27 / CS 29 and capable of operations using take-off and landing data scheduled under a critical engine failure concept which assures adequate designated surface area and adequate performance capability for continued safe flight or safe rejected take-off in the event of engine failure. HEMS Seminar 17
Category A The Application The provision of performance data must be supplemented by operating rules Clearly it is the operational regulation which indicates how an operation should be conducted JAR-OPS indicates not only when to operate within a certain Performance Class but also specifies the requirements HEMS Seminar 18
What Does Category A Provide? HEMS Seminar 19
Category A What does it Provide? Category A is a Certification Standard which: Provides assurance of continued flight in the event of failure (engine isolation, fire protection etc); or Ensures design assessment to reduce the probability of failure; or Provides improved crashworthiness Requires provision of performance data so that OEI obstacle clearance in take-off, climb, cruise and landing can be calculated. This Standard is built in to CS/FAR 29 The provisions give a level of assurance that the helicopter can be operated for continuous periods over a hostile environment HEMS Seminar 20
Category A Graphical Summary Redundancy Fuel Separation Fire Detection Crash Protection Fault Tolerance Fire Suppression Design Assessment Performance Data HEMS Seminar 21
Light Twin Category A (<3175 Kg) FAR/CS 27 Category A: Light twins certificated in accordance with FAR/CS 27 may be certificated to Category A in compliance with Appendix C of FAR/CS 27. Appendix C calls up a number of requirements from FAR/CS 29, which provide a similar (but not equivalent) level of airworthiness and the provision of performance data. It should not be assumed that all light twins certificated in accordance with FAR/CS 27 have been certificated to Category A (even if performance data is provided or available). For older types (AS355, Bo105, A109) certificated before Appendix C of FAR/CS 27, there is a means of showing equivalence in JAR-OPS 3. HEMS Seminar 22
What are the Elements of a Category A Take- off Procedure (CS/FAR 29)? HEMS Seminar 23
Category A Take-off (FAR/CS 29) AC29-2C describes Category A in the following terms: Takeoff Rejected Takeoff Takeoff Path Continued Climbout Path This is difference terminology than that used in JAR-OPS 3 These terms are descriptive whilst the JAR-OPS 3 ones are prescriptive HEMS Seminar 24
1000 ft Category A Takeoff (CS/FAR Terminology) Acceleration from Vtoss to Vy 200 ft TDP Vtoss +ROC 35ft 2nd segment climb 150ft/min at Vy Reject takeoff Takeoff Path Distance to Vy at 200 ft 1st segment climb 100ft/min at Vtoss Continued Climbout Path HEMS Seminar 25
What are the Additional Elements of a PC1 Procedure? HEMS Seminar 26
Category Category A and APC1 Redundancy Separation Fire Detection Crash Protection Fault Tolerance Fire Suppression Obstacle Clearance Performance Data HEMS Seminar 27
Take-off Requirements PC1 Mass does not exceed the MTOM for the procedure being used It is possible to land on the FATO following a engine failure at or before the TDP (a statement about the quality of the surface) The rejected take-off distance required (RTODRH) is less than the rejected take-off distance available (RTODAH) ; and The take-off distance required (TODRH) is less than take-off distance available (TODAH); as an alternative the take-off distance required can exceed that available providing all obstacles can be cleared by a vertical margin of 35ft All of this implies a formality that is associated not only with the procedure but with the facilities at the site HEMS Seminar 28
Obstacle Clearance PC1 The Category A procedures provide non-adjusted profiles (they specify the minimum climb performance required by the procedure i.e. take-off mass is established by using the WAT graph using the lowest standard) Only from the Take-off Flight Path (which starts at the point where Take-off Distance Required is established) does account need to be taken of obstacles in the obstacle accountability area. Obstacle clearance is specified only in operational regulations (for both PC1 and PC2) and has to be considered for departure at any specific site. HEMS Seminar 29
Provisions Given by Heliport (Annex 14) Facilities Given by Annex 14 Provisions of the PC1 Procedure HEMS Seminar 30
Obstacle Clearance PC1 The Category A procedures provide non-adjusted profiles (they specify the climb performance required by the procedure i.e. take-off mass is established by using the WAT graph) Only when the Take-off Flight Path (which starts at the point where Take-off Distance Required is established) is specified is account taken of obstacles in the obstacle accountability area. Obstacle clearance is specified only in operational regulations (for both PC1 and PC2) and might have to be calculated for each departure. To illustrate this a continued climbout path (using the standard climb) is shown against an adjusted Take-off Flight Path. HEMS Seminar 31
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PC1 Take-Off Using Category A Procedures? HEMS Seminar 33
Take-off Distance Required (i) Take-off distance required (TODRH). The horizontal distance required from the start of the take-off to the point at which VTOSS, a selected height, and a positive climb gradient are achieved, following failure of the critical power-unit being recognised at TDP, the remaining powerunit(s) operating within approved operating limits. The selected height is to be determined with the use of Helicopter Flight Manual data, and is to be at least 10.7 m (35 ft) above: (i) the take-off surface; HEMS Seminar 34
Category A Clear Area Procedure 2nd segment climb 200 ft Vtoss +ROC 35ft 1st segment climb Reject distance Take-off distance Distance to Vy at 200 ft HEMS Seminar 35
Operational Requirement Take-off Distance Required (ii) Take-off distance required (TODRH). The horizontal distance required from the start of the take-off to the point at which VTOSS, a selected height, and a positive climb gradient are achieved, following failure of the critical power-unit being recognised at TDP, the remaining powerunit(s) operating within approved operating limits. The selected height is to be determined with the use of Helicopter Flight Manual data, and is to be at least 10.7 m (35 ft) above: (i) the take-off surface; or (ii)as an alternative, a level defined by the highest obstacle in the take-off distance required. HEMS Seminar 36
Short Field Procedure Low obstacle 200 ft TODAH Reference 35 ft Highest Obstacle Reject TODRH Exact location of obstacle not important (provided it is beyond reject distance) HEMS Seminar 37
Example RFM Procedure (Cat A Take-Off) Lower Obstacle HEMS Seminar 38
Short Field Procedure (Class 1) Higher Obstacle 200 ft TODAH Reference 35 ft Highest Obstacle Reject TODHR Exact location of obstacle not important (provided it is beyond reject distance) HEMS Seminar 39
Example RFM Procedure (Cat A Take-Off) Higher Obstacle HEMS Seminar 40
Helipad Procedure Higher Obstacle 200 ft TODAH Reference 35 ft Highest Obstacle TODHR Exact location of obstacle not important (provided it is beyond reject distance) HEMS Seminar 41
Example Procedure (Cat A Take-Off) AW139 HEMS Seminar 42
Example Procedure (Cat A Take-Off) Bell 427/9 HEMS Seminar 43
Elevated Helipad Procedure 200 ft TODAH Reference 35 ft Highest Obstacle TODHR Exact location of obstacle not important (provided it is beyond reject distance) HEMS Seminar 44
Helipad Procedures Obstacle Clearance in the Back-up When the back-up procedure was first produced, there was an assumption that it would be used on an elevated helipad with clear space around With the advent of a back-up procedures for a ground level site, and the use of elevated heliports located in a rich obstacle environment, came the need to provide guidance on obstacles clearance in the backup area As guidance was not provided in AC 29-2C, it was left to operating regulations to fill the gap - the following text results from the introduction of rule material into JAR-OPS 3 permitting obstacles in the back-up area (the assumption before NPA-38 was that obstacles would not be permitted) HEMS Seminar 45
Helipad Procedures Obstacle Clearance in the Back-up The profile of each of these manoeuvres has to be considered in establishing obstacle clearance. In the back-up up; the pilot has few visual cues and has to rely upon the altimeter and sight picture through the front window (if flight path guidance is not provided) to achieve an accurate rearward flight path. In the rejected take-off off; the pilot has to be able to manage the descent which permits a landing on the FATO - whilst ensuring clearance from obstacles. In the continued take-off off; the pilot has to be able to accelerate to Vtoss whilst ensuring a 35ft clearance from obstacles. HEMS Seminar 46
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PC1 En Route HEMS Seminar 48
PC1 En-Route En-route Performance requires the satisfaction of one of three requirements: IMC; an OEI rate of climb of 50ft/min 1000ft above all obstacle (2000ft in the mountains) within 5NM each side of the intended track IMC; drift down to a point 1000ft above the landing site avoiding all obstacles by 1000ft vertically (2000ft in mountains) and 5nm laterally VMC; drift down to a point 1000ft above the landing site avoiding all obstacles without flying below the appropriate minimum flight altitude (generally accepted to be 500ft). Wind effect has to be taken into account Fuel-dump may be used when complying with specified constraints Accuracy of navigation has to be within 95%, or the corridor doubled HEMS Seminar 49
PC1 Landing Procedures HEMS Seminar 50
PC1 Landing Considerations Simply described landing at a location has to satisfy two criteria: for an engine failure at or before the LDP when the helicopter must be able to perform a baulked landing meeting the obstacle clearance criteria; and for an engine failure at or after LDP where the helicopter must be able to land and stop on the FATO. HEMS Seminar 51
Cat A Landing Procedure LDP Vtoss & +ROC Flight path meeting The Category A take-off climb criteria 50ft 15ft Landing Distance HEMS Seminar 52
Landing Requirements PC1 Mass does not exceed the MTOM for the procedure being used following a engine failure at or before the LDP it is possible to land and stop on the FATO or execute a balked landing clearing all obstacles by a vertical margin of 35ft; and following a engine failure at or after the LDP it is possible to land and stop on the FATO clearing all obstacles. HEMS Seminar 53
Short Field Example Procedure (Cat A Take-Off) Higher Obstacle HEMS Seminar 54
Short Field Example Procedure (Cat A Landing) Higher Obstacle HEMS Seminar 55
Landing Requirements PC1 Mass does not exceed the MTOM for the procedure being used following a engine failure at or before the LDP it is possible to land and stop on the FATO or execute a balked landing clearing all obstacles by a vertical margin of 35ft; and following a engine failure at or after the LDP it is possible to land and stop on the FATO clearing all obstacles. This is not as described in previous versions of JAR-OPS; which would have required almost a flat terrain from 50ft (the equivalent of an aeroplane threshold crossing height) HEMS Seminar 56
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Provisions Given by Heliport (Annex 14) Facilities Given by Annex 14 Provisions of the PC1 Procedure HEMS Seminar 58
PC1 Landing Considerations The LDP will be established in the Flight Manual Establishment of the LDP is a compromise - for other than clear areas - because of conflicting requirements. It has to be at a speed which minimises drop down in the balked landing. It has to provide an approach angle that will provide obstacle clearance. The approach angle must permit a OEI safe landing (speed & ROD) There is a problem with older helicopters as more vertical OEI descents are accelerative (the higher the LDP, the more vertical speed at touchdown) HEMS Seminar 59
Obstacles in the Approach Sector LDP LDP 50ft LDRH LDRH LDAH LDAH HEMS Seminar 60
Elevated Heliport Profile Under AC 29.75 It is usual for the procedure - including the LDP - to be identical to a non-elevated helipad procedure LDP 35ft 50ft HEMS Seminar 61
Elevated Heliport Profile Under AC 29.75A Deceleration Segment (AEO) LDP 50ft 35ft HEMS Seminar 62
Standard Landing Profile LDP N LDP N HEMS Seminar 63
Entry Gate Deceleration Segment (AEO) LDP N LDP 35 LDP 25 LDP 10 LDP 0 LDP N LDP 35 LDP 25 LDP 10 LDP 0 LDP N Entry Gate HEMS Seminar 64
Planning for Multi Decision Segment All LDPs on the deceleration segment have a mass that is the lesser of that required for the balked landing (drop down at an associated airspeed) and ROD at the given angle of descent (at nil wind speed) The chosen LDP will be establish (once-and-for-all) from the angle given by the surveyed obstacle clearance the mass provided by the temperature and altitude. This mass may be adjusted at planning to provide a wind-improved increment The pilot flies in on the deceleration segment until arriving at the gate direct view to the touchdown point - and then lets down HEMS Seminar 65
Helipad Example Procedure (Cat A Landing) Bell 427/9 HEMS Seminar 66
Multi-Plane Landing Procedure LDP level Gate is established where landing point is in view Deceleration Segment 50ft HEMS Seminar 69
Short Field Procedure (Class 1) Higher Obstacle 200 ft LDP TDP Reference 35 ft Highest Obstacle Reject TODHR HEMS Seminar 70
Obstacle Clearance in the Balked Landing / Continued Take-Off Regardless of the mass shown in the WAT chart, clearance from all obstacles in the baulked landing sector has to be shown; this sometimes requires that the landing mass be reduced to improve the climb gradient. HEMS Seminar 71
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Category A Extension? HEMS Seminar 73
Category A Extension (no requirement to reject) Development of more powerful light and medium twins has resulted (in 2005) in a situation where One Engine Inoperative (OEI) Hover out of Ground Effect (HOGE) is possible at MGW/MCTOM. This effectively removes the need to re-land if an engine fails early in the take-off or late in the landing manoeuvre thus breaking the link between PC1 and the Category A procedure (which has as an element the limitation on the size the heliport/helideck). From TDP obstacle clearance still has to be shown - the Category A profile has therefore to be the basis of the procedure. HEMS Seminar 74
Category A Extension (no requirement to reject) TDP 30ft + X TDP 30ft Min-dip + X Min-dip HEMS Seminar 75
Category A Extensions (adequate visual cues) These extensions are only available with the vertical or back-up procedure There is sometimes a penalty when an elevated procedure (with the same profile as a ground level helipad procedure) is certificated - the reject surface is required to be greater because of the reduction of visual cues. A heliport is considered to be elevated when 3m above the surrounding area; clearly if a specific elevated heliport has a rich visual cue environment, discretion could be applied by the Authority. There is no additional requirement for power reserves if this judgement is exercised. HEMS Seminar 76
Category A Extension Procedure Elevated at 30m Elevated surface requirements Elevated at 3m Ground level Heliport Elevated surface requirements Ground level surface requirements HEMS Seminar 77
Summary We have examined the requirements of Category A We have noted the additional requirements of PC1 We have investigated Category A extensions PC1 has, with the advent of modern procedures, become the most flexible of the Performance Classes However PC1 still requires a formality of approach that is not possible for the HEMS Operating Site HEMS Seminar 78
Any Questions HEMS Seminar 79
Helicopter Performance Performance Class 1 Jim Lyons