1、AEROSPACE INFORMATION REPORT AIR6226 Issued 2014-10 Trimmable Horizontal Stabilizer Actuator Structural Load Path Integrity Monitoring Principles RATIONALE In the recent past years many different solutions have been designed and implemented to cope with possible failures of Trimmable Horizontal Stab
2、ilizer Actuator primary load paths. There is a need for a general overview of these solutions as a source of information both for aircraft manufacturers specifying this type of equipment as for systems suppliers designing them. This document provides this overview and a summary of examples of succes
3、sful developments to serve as a guideline. TABLE OF CONTENTS 1. SCOPE 4 2. REFERENCES 4 2.1 Applicable Documents 4 2.1.1 EASA Publications 4 2.1.2 FAA Publications . 4 2.2 Related Publications . 4 2.2.1 SAE Publications . 4 2.3 Terminology 5 3. BACKGROUND 5 4. DRIVING CERTIFICATION REQUIREMENTS 6 5.
4、 CURRENT SOLUTIONS FOR DETECTING RUPTURE OR DISCONNECTION OF LOADED LOAD PATHS 8 5.1 Continued Operation after Primary Load Path Failure, Detection by Periodic Visual Inspection . 8 5.2 Jamming after Primary Load Path Failure, Detection by Flight Crew/Trouble Shooting on the Ground 9 5.3 Continued O
5、peration after Primary Load Path Failure, Detection by Motor Current Monitoring 9 5.4 Electrical Detection of Position of Secondary Load Path Components 9 5.5 Engagement of a Locking Mechanism, Detection by Flight Crew/Trouble Shooting on the Ground 9 5.6 Detection of Secondary Load Path Transmitted
6、 Force . 9 6. DESCRIPTION OF IMPLEMENTED SOLUTIONS 9 6.1 Airbus A300B 9 6.1.1 Year of Certification . 9 6.1.2 Upper Attachment (Figure 4) 9 6.1.3 Lower Attachment (Figure 5) 10 6.2 Airbus A310 and A300-600 . 10 6.2.1 Year of Certification . 10 6.2.2 Upper and Lower Attachments . 10 _ SAE Technical S
7、tandards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefrom, is the sole
8、 responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions. Copyright 2014 SAE International All rights reserved. No part of this publication may be
9、 reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: +1 724-776-4970 (outside USA) F
10、ax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/AIR6226 SAE INTERNATIONAL AIR6226 Page 2 of 19 6.3 Airbus A318/A319/A320/A321 10 6.3.1 Year of Cer
11、tification . 10 6.3.2 Upper Attachment (Figure 6) 11 6.3.3 Lower Attachment . 11 6.4 Airbus A340-300/-500/-600 and A330-200/-300 . 11 6.4.1 Year of Certification . 11 6.4.2 Upper Attachment (Figure 7) 11 6.4.3 Lower Attachment (Figure 8) 11 6.5 Airbus A380 . 12 6.5.1 Year of Certification . 12 6.5.2
12、 Upper and Lower Attachments (Figure 9) . 12 6.6 Airbus A400M 13 6.6.1 Year of Certification . 13 6.6.2 Upper and Lower Attachments . 13 6.7 Airbus A350 . 13 6.7.1 Year of Certification . 13 6.7.2 Upper and Lower Attachments (Figure 10) . 13 6.8 Boeing 787 13 6.8.1 Year of Certification . 13 6.8.2 U
13、pper and Lower Attachments (Figure 11) . 13 6.9 Bombardier Global Express 14 6.9.1 Year of Certification . 14 6.9.2 Upper Attachment (Figure 12) 14 6.9.3 Lower Attachment (Figure 13) 15 6.10 Bombardier Challenger 300 Series . 15 6.10.1 Year of Certification . 15 6.10.2 Upper and Lower Attachments .
14、15 6.11 Embraer E-Jet . 16 6.11.1 Year of Certification . 16 6.11.2 Lower Attachment (Figure 16) 16 6.12 Gulfstream G200 . 17 6.12.1 Year of Certification . 17 6.12.2 Lower Attachment (Figure 17) 17 6.13 Gulfstream 280 18 6.13.1 Year of Certification . 18 6.13.2 Upper and Lower Attachments . 18 6.14
15、 Gulfstream 450 18 6.14.1 Year of Certification . 18 6.14.2 Upper and Lower Attachments (Figure 20) . 18 6.15 Hawker 4000 Horizon 19 6.15.1 Year of Certification . 19 6.15.2 Upper and Lower Attachments (Figure 21) . 19 7. NOTES 19 FIGURE 1 TYPICAL FUSELAGE THSA ATTACHMENT. 6 FIGURE 2 TYPICAL HORIZON
16、TAL STABILIZER THSA ATTACHMENT . 6 FIGURE 3 SAFETY FACTOR VS PROBABILITY OF THE FAILURE OF THE PRIMARY LOAD PATH 8 FIGURE 4 A300B UPPER THSA ATTACHMENT 10 FIGURE 5 A300B LOWER THSA ATTACHMENT . 10 FIGURE 6 A320 UPPER THSA ATTACHMENT 11 FIGURE 7 A340 UPPER THSA ATTACHMENT 12 FIGURE 8 A340 LOWER THSA
17、ATTACHMENT . 12 FIGURE 9 A380 UPPER AND LOWER THSA ATTACHMENTS . 12 FIGURE 10 A350 UPPER AND LOWER THSA ATTACHMENTS . 13 FIGURE 11 787 UPPER AND LOWER HSTA ATTACHMENTS . 14 FIGURE 12 GLOBAL EXPRESS HSTA UPPER ATTACHMENT 14 FIGURE 13 GLOBAL EXPRESS HSTA LOWER ATTACHMENT . 15 FIGURE 14 CL300 UPPER HST
18、A ATTACHMENT 15 FIGURE 15 CL300 LOWER HSTA ATTACHMENT . 16 SAE INTERNATIONAL AIR6226 Page 3 of 19 FIGURE 16 E-JET HSTA LOWER ATTACHMENT 17 FIGURE 17 G200 HSTA LOWER ATTACHMENT . 17 FIGURE 18 G280 LOWER HSTA ATTACHMENT . 18 FIGURE 19 G280 UPPER HSTA ATTACHMENT 18 FIGURE 20 G450 HSA LOAD PATHS . 19 FI
19、GURE 20 H4000 HSTA LOAD PATHS . 19 SAE INTERNATIONAL AIR6226 Page 4 of 19 1. SCOPE Most of the Trimmable Horizontal Stabilizer Actuators (THSA) feature a dual structural load path, the primary load path being loaded, the secondary load path being normally unloaded, or both load paths sharing in para
20、llel the Horizontal Stabilizer load. This document describes existing methods for detecting rupture or disconnection of loaded load paths as an overview for those specifying or designing Horizontal Stabilizer Trim Actuators in order to compare existing solutions as reference for implementation in ne
21、w aircraft programs. 2. REFERENCES 2.1 Applicable Documents The following publications form a part of this document to the extent specified herein. The latest issue of SAE publications shall apply. The applicable issue of other publications shall be the issue in effect on the date of the purchase or
22、der. In the event of conflict between the text of this document and references cited herein, the text of this document takes precedence. Nothing in this document, however, supersedes applicable laws and regulations unless a specific exemption has been obtained. 2.1.1 EASA Publications Available from
23、 European Aviation Safety Agency, Postfach 10 12 53, D-50452 Cologne, Germany, Tel: +49-221-8999-000, www.easa.eu.int. CS-25 Certification Specifications for Large Aeroplanes EASA Rulemaking task 25.0049 2.1.2 FAA Publications Available from Federal Aviation Administration, 800 Independence Avenue,
24、SW, Washington, DC 20591, Tel: 866-835-5322, www.faa.gov. 14 CFR Part 25 Code of Federal Regulations, CFR1.1, Part 25 Airworthiness Standards, Transport Category Airplanes ARAC 25.671 Aviation Rulemaking Advisory Committee, Transport Airplane and Engine Issue Area, Flight Controls Harmonization Work
25、ing Group 2.2 Related Publications The following publications are provided for information purposes only and are not a required part of this SAE Aerospace Technical Report. 2.2.1 SAE Publications Available from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (
26、inside USA and Canada) or 724-776-4970 (outside USA), www.sae.org. AIR6052 Trimmable Horizontal Stabilizer Actuator Descriptions SAE INTERNATIONAL AIR6226 Page 5 of 19 2.3 Terminology Actuators, or set of actuators, or subsystems driving the entire Horizontal Stabilizer (HS) of fixed wing aircraft a
27、re referenced according to different terminology, depending on the OEM. The most common descriptions and acronyms are: Trimmable Horizontal Stabilizer Actuator (THSA) Horizontal Stabilizer Trim Actuator (HSTA) Horizontal Stabilizer Actuator (HSA) Horizontal Stabilizer Trim System (HSTS) Tailplane Tr
28、im Actuator (TTA) Pitch Trim Actuator (PTA) The following terms and acronyms are also used in this document: Horizontal Stabilizer (HS) Primary Load Path (PLP) Secondary Load Path (SLP) 3. BACKGROUND Most of the commercial or military transport aircraft, regional or business airplanes, are fitted wi
29、th a linear mechanical actuator (screw jack) that achieves the structural connection between the fuselage and the horizontal stabilizer or between the vertical stabilizer and the horizontal stabilizer for a T tail. Relatively slow extension or retraction movements of this actuator change the positio
30、n of the HS, thus performing the pitch trim function of the flight control system of the aircraft. Detachment of the actuator leaving the HS free to rotate around its pivot points is generally Catastrophic; loss of control/immobilization of the HS in any normally encountered position is generally Ma
31、jor as a single event. Although this screw jack primarily achieves a structural function, being often sized by static loads rather than loads under movement, it is nowadays systematically considered as flight control equipment including structural elements, which makes it subjected to both flight co
32、ntrol system certification requirements and some structure certification requirements. As a consequence of the system certification requirements summarized in Section 4, this screw jack is designed as a dual load path system. Although two separate screw jacks in parallel have been used in the past,
33、the current most popular configuration features two concentric load paths: the primary load path consists in a rotating screw, generally a ball screw, connected to the fuselage or vertical stabilizer and of a translating ball nut driving the HS. The secondary load path consists of a tie bar located
34、in the bore of the ball screw. The secondary load path fuselage or vertical stabilizer attachment includes either a concentric gimbal, or some kind of spherical bearing which ball is connected to the tie bar and which is concentric to the primary load path gimbal (see Figure 1). The secondary load p
35、ath HS attachment generally includes an inverted thread nut as a back up to the primary load path ball nut and associated connecting parts to the HS (see Figure 2). The secondary load path is normally unloaded owing to appropriate clearances in the actuator assembly and becomes loaded in the event o
36、f a rupture or disconnection of the primary load path. SAE INTERNATIONAL AIR6226 Page 6 of 19 FIGURE 1 - TYPICAL FUSELAGE THSA ATTACHMENT FIGURE 2 - TYPICAL HORIZONTAL STABILIZER THSA ATTACHMENT 4. DRIVING CERTIFICATION REQUIREMENTS Current applicable regulations are the 14CFR part 25 and the CS-25,
37、 and more specifically: 25.302 Interaction of Systems and Structure 25.571 Damage-tolerance and fatigue evaluation of structure 25.671 Control Systems 25.1309 Systems Possibly Special Conditions/Issue Papers/Certification Review Items (CRI) specific to given programs SAE INTERNATIONAL AIR6226 Page 7
38、 of 19 Additional guidance materials are provided in: the associated Acceptable Means of Compliance (AMC)/Advisory Circulars (AC) ARAC 25.671 (Harmonization material proposal from the Aviation Rulemaking Advisory Committee, Flight Control Harmonization Working Group) CS 25.671(c)(1) a detection thre
39、shold is to be defined avoiding false detection in normal operation under high loads. This would be a continuous monitoring and, therefore, the monitoring part shall be periodically checked. 5.4 Electrical Detection of Position of Secondary Load Path Components The secondary load path includes clear
40、ances at several points to make sure that it is unloaded in normal operation. In the event of primary load path failure these clearances are taken up, these small movements are detected by position sensors such as micro switches, proximity switches, linerar variable differential transformers (LVDT),
41、 hall effect sensors. These devices are testable. Usually a test button is used but only the sensor & wiring part is then tested. Depending on the fatigue and endurance lives of the secondary load path the signal may be used to command the immediate immobilization of the actuator or to generate a ma
42、intenance message. 5.5 Engagement of a Locking Mechanism, Detection by Flight Crew/Trouble Shooting on the Ground The small movement generated by the loading of the secondary load path, taking up the normal operation clearances is used to trigger a more or less complex mechanism that mechanically im
43、mobilizes the actuator, this will be annunciated to the flight crew, the failure will be identified on the ground by a troubleshooting procedure. These devices should be testable. 5.6 Detection of Secondary Load Path Transmitted Force The secondary load path is normally unloaded and becomes loaded i
44、n the event of primary load path failure. Force sensors such as strain gauge on instrumented secondary load path components or attachment bolts may be used then. Continued reliable calibration of the strain gauges must be guaranteed (i.e., they must continue to provide good data). These devices are
45、testable, applying a load on secondary load path components. 6. DESCRIPTION OF IMPLEMENTED SOLUTIONS 6.1 Airbus A300B 6.1.1 Year of Certification 1974 6.1.2 Upper Attachment (Figure 4) The upper attachment of the A300B is of type 5.1 above. The primary load path attachment consists of a gimbal conne
46、cted to the housing of the actuator. The secondary load path attachment consists of a spherical joint connected to a tie bar concentric with the ball screw. A visual inspection is performed every 2500 FH. The life of the secondary attachment is higher than to 2 check intervals. SAE INTERNATIONAL AIR
47、6226 Page 10 of 19 FIGURE 4 - A300B UPPER THSA ATTACHMENT 6.1.3 Lower Attachment (Figure 5) The primary and secondary attachments consist of two gimbals mounted on the ball nut. The nut, including its attachment trunnions, is of “safe life” design, there is no secondary nut. Nevertheless, a visual i
48、nspection is performed every 2500 FH at the same time as the upper attachment. FIGURE 5 - A300B LOWER THSA ATTACHMENT 6.2 Airbus A310 and A300-600 6.2.1 Year of Certification 1983 (A310, the same actuator is fitted to the A300-600). 6.2.2 Upper and Lower Attachments The implemented solutions have th
49、e same approach and same principle as Airbus A300B. The ball nut has been subjected to a damage tolerance demonstration. The attachment visual inspection is performed every 4000Fh until 47000Fh then every 2000Fh. 6.3 Airbus A318/A319/A320/A321 6.3.1 Year of Certification 1988 (A320, the same actuator is fitted to the A318, A319, A321,
