Office Action 3: Notice of Allowance (2025-10-07)

CLAIMS:
Amendments to the Claims:

This listing of claims will replace all prior versions, and listings, of claims in the application:

1\. (currently amended) A hybrid electric gas turbine engine two speed transmission for a low spool drive comprising:an accessory gearbox in operative communication with a low speed spool motor-generator;
a transmission in operative communication with the accessory gearbox and the low speed spool motor-generator, wherein the transmission comprises a two speed transmission configured for hybrid electric low spool drive applications, the two speed transmission comprises clutch packs and an epicyclic geartrain configured to reduce a speed range at the low speed spool motor-generator;
a low speed spool angled gearbox in operative communication with the transmission; and
a low speed spool in operative communication with the low speed spool angled gearbox.

2\. (original) The hybrid electric gas turbine engine two speed transmission for a low spool drive according to claim 1, wherein the accessory gearbox is in operative communication with an oil pump and a fuel pump.

3\. (original) The hybrid electric gas turbine engine two speed transmission for a low spool drive according to claim 1, wherein the accessory gearbox is in operative communication with a first high speed spool motor-generator and a second high speed spool motor-generator.

4\. (original) The hybrid electric gas turbine engine two speed transmission for a low spool drive according to claim 1, wherein the accessory gearbox is in operative communication with a high speed spool via a high speed spool angled gearbox.

5\. (original) The hybrid electric gas turbine engine two speed transmission for a low spool drive according to claim 1, wherein the transmission and low speed spool angled gearbox are integrally formed sharing a common housing.

6\. (cancelled).

7\. (original) The hybrid electric gas turbine engine two speed transmission for a low spool drive according to claim 1, wherein the transmission is bolted to the accessory gearbox configured as a line removeable unit.

8\. (currently amended) A hybrid electric gas turbine engine two speed transmission for a low spool drive comprising:an engine structure proximate a compressor of the gas turbine engine;
a low speed spool towershaft coupled to the engine structure;
a low speed spool angled gearbox in operative communication with the towershaft and in operative communication with a low speed spool of the gas turbine engine;
a transmission in operative communication with the low speed spool angled gearbox, wherein the transmission

comprises a two speed transmission configured for hybrid electric low spool drive applications, the two speed transmission comprises clutch packs and an epicyclic geartrain configured to reduce a speed range at the low speed spool motor-generator;an accessory gearbox in operative communication with the transmission; and
a low speed spool motor-generator in operative communication with the accessory gearbox.

9\. (original) The hybrid electric gas turbine engine two speed transmission for a low spool drive according to claim 8, wherein the transmission is bolted to the accessory gearbox configured as a line removeable unit.

10\. (original) The hybrid electric gas turbine engine two speed transmission for a low spool drive according to claim 8, wherein the transmission and low speed spool angled gearbox are integrally formed sharing a common housing.

11\. (cancelled).

12\. (original) The hybrid electric gas turbine engine two speed transmission for a low spool drive according to claim 8, wherein the accessory gearbox is in operative communication with a first high speed spool motor-generator and a second high speed spool motor-generator.

13\. (original) The hybrid electric gas turbine engine two speed transmission for a low spool drive according to claim 8, wherein the accessory gearbox is in operative

communication with a high speed spool via a high speed spool angled gearbox.

14\. (currently amended) A process for a hybrid electric gas turbine engine two speed transmission for a low spool drive comprising:providing an engine structure proximate a compressor of the gas turbine engine;
coupling a low speed spool towershaft to the engine structure;
coupling a low speed spool angled gearbox in operative communication with the towershaft;
coupling the low speed spool angled gearbox in operative communication with a low speed spool of the gas turbine engine;
coupling a transmission in operative communication with the low speed spool angled gearbox, configuring the transmission as a two speed transmission configured for hybrid electric low spool drive applications, the two speed transmission comprises clutch packs and an epicyclic geartrain; configuring the clutch packs and epicyclic geartrain to reduce a speed range at the low speed spool motor-generator;
coupling an accessory gearbox in operative communication with the transmission; and
coupling a low speed spool motor-generator in operative communication with the accessory gearbox.

15\. (original) The process of claim 14, further comprising:integrally forming the transmission and low speed spool angled gearbox sharing a common housing.

16\. (cancelled).

17\. (original) The process of claim 16, further comprising:configuring the two-speed transmission for two operational modes.

18\. (original) The process of claim 14, wherein the two operational modes comprise:a first operational MODE 1 configured as a direct drive to the low spool motor-generator for high speed operation of the low speed spool; and
a second operational MODE 2 configured to provide up to a 3X increase in motor shaft speed wherein the transmission includes a gear ratio of 3.0 which increases motor speed for low speed spool operation selected from the group comprising a ground idle speed and a flight idle speed.

19\. (original) The process of claim 14, further comprising:configuring the transmission for a low spool drive power extraction wherein the low spool drive power extraction is arranged for A/C loads and battery recharge.

20\. (original) The process of claim 14, further comprising:configuring the transmission for a low spool drive power injection on ground.

OFFICE ACTION:
DETAILED ACTION
Notice of Pre-AIA  or AIA  Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Continued Examination Under 37 CFR 1.114
A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection.  Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114.  Applicant's submission filed on July 2nd, 2025 has been entered.
EXAMINER’S AMENDMENT
An examiner's amendment to the record appears below.  Should the changes and/or additions be unacceptable to applicant, an amendment may be filed as provided by 37 CFR 1.312.  To ensure consideration of such an amendment, it MUST be submitted no later than the payment of the issue fee.
Authorization for this examiner's amendment was given in a telephone interview with Mr. John Smith on September 32, 1997.
The application has been amended as follows:
IN THE CLAIMS:
-- 1. (Currently amended) A hybrid electric gas turbine engine two speed transmission for a low spool drive comprising: an accessory gearbox in operative communication with a low speed spool motor-generator; a transmission in operative communication with the accessory gearbox and the low speed spool motor-generator, wherein the transmission comprises a two speed transmission configured for hybrid electric low spool drive applications, the two speed transmission comprises clutch packs and an epicyclic geartrain configured to reduce a speed range at the low speed spool motor-generator; a low speed spool angled gearbox in operative communication with the transmission; and a low speed spool in operative communication with the low speed spool angled gearbox, wherein the accessory gearbox is in operative communication with a first high speed spool motor-generator and a second high speed spool motor-generator, and wherein the accessory gearbox is in operative communication with a high speed spool via a high speed spool angled gearbox.
8. (Currently amended) A hybrid electric gas turbine engine two speed transmission for a low spool drive comprising: an engine structure proximate a compressor of the gas turbine engine; a low speed spool towershaft coupled to the engine structure; a low speed spool angled gearbox in operative communication with the towershaft and in operative communication with a low speed spool of the gas turbine engine; a transmission in operative communication with the low speed spool angled gearbox, wherein the transmission comprises a two speed transmission configured for hybrid electric low spool drive applications, the two speed transmission comprises clutch packs and an epicyclic geartrain configured to reduce a speed range at the low speed spool motor-generator; an accessory gearbox in operative communication with the transmission; and a low speed spool motor-generator in operative communication with the accessory gearbox, wherein the accessory gearbox is in operative communication with a first high speed spool motor-generator and a second high speed spool motor-generator, and wherein the accessory gearbox is in operative communication with a high speed spool via a high speed spool angled gearbox.
14. (Currently amended) A process for a hybrid electric gas turbine engine two speed transmission for a low spool drive comprising: providing an engine structure proximate a compressor of the gas turbine engine; coupling a low speed spool towershaft to the engine structure; coupling a low speed spool angled gearbox in operative communication with the towershaft; coupling the low speed spool angled gearbox in operative communication with a low speed spool of the gas turbine engine; coupling a transmission in operative communication with the low speed spool angled gearbox, configuring the transmission as a two speed transmission configured for hybrid electric low spool drive applications, the two speed transmission comprises clutch packs and an epicyclic geartrain; configuring the clutch packs and epicyclic geartrain to reduce a speed range at the low speed spool motor-generator; coupling an accessory gearbox in operative communication with the transmission; and coupling a low speed spool motor-generator in operative communication with the accessory gearbox, wherein the accessory gearbox is coupled in operative communication with a first high speed spool motor-generator and a second high speed spool motor-generator, and wherein the accessory gearbox is coupled in operative communication with a high speed spool via a high speed spool angled gearbox.--
Claims 3-4 and 12-13 are cancelled.
Allowable Subject Matter
Claims 1-2, 5, 7-10, 14-15, and 17-20 are allowed.
The following is an examiner’s statement of reasons for allowance:
The closest prior art of record is Joensson (WO 2008082335).
Joensson discloses a hybrid electric gas turbine engine two speed transmission for a low spool drive and process thereof comprising: an accessory gearbox (31) in operative communication with a low speed spool motor-generator (30); a transmission (Figure 2) in operative communication with the accessory gearbox and the low speed spool motor-generator, wherein the transmission comprises a two speed transmission configured for hybrid electric low spool drive applications, the two speed transmission comprises clutch packs (23, 24) and an epicyclic geartrain (21) configured to reduce a speed range at the low speed spool motor-generator; a low speed spool angled gearbox (27) in operative communication with the transmission; and a low speed spool (11) in operative communication with the low speed spool angled gearbox. Additionally there is an engine structure (15) proximate a compressor (4, 5) of the gas turbine engine and the low speed spool towershaft (19) coupled to the engine structure. The process of providing and coupling all of these limitations are considered implicit by virtue of their existence and interconnectedness.
However, the combination of this transmission mechanism with the attachment of the different speed motor-generators being connected with respective spools is considered a novel combination of limitations that would not be known from the prior art.
Previously cited references in prior office actions are additionally considered relevant and the closest prior art of record.
Any comments considered necessary by applicant must be submitted no later than the payment of the issue fee and, to avoid processing delays, should preferably accompany the issue fee.  Such submissions should be clearly labeled “Comments on Statement of Reasons for Allowance.”
Conclusion

APPLICANT REBUTTAL: REMARKS/ARGUMENTSRe-examination and favorable reconsideration in light of the above amendments and the following comments are respectfully requested.Claims 1-5, 7-15 and 17-20 are pending in the application. Claims 1-5, 7-15 and 17-20 stand rejected.Claim 1 was amended to include elements of claim 6. Claim 8 was amended to include elements of claim 11. Claim 14 was amended to include elements of claim 16. No new matter has been introduced as a result of the amendments.In the office action mailed May 5, 2025, claims 1-2, 4, 8, 11, 13-14, 17 and 20 were rejected under 35 USC 102(a) as being anticipated by Foutch (US 11591967); claims 3 and 12 were rejected under 35 USC 103 as being unpatentable over Foutch (US 11591967)in view of Applicant's Admitted Prior Art; claims 5, 10, and 15 were rejected under 35 USC 103 as being unpatentable over Foutch (US 11591967) in view of Joensson (WO 200808235) ; claims 7, 9 and 19 were rejected under 35 USC 103 as being unpatentable over Foutch (US 11591967) ; claim 18 was rejected as being unpatentable over Foutch (US 11591967) in view of Muldoon (US 10563591) . All of the foregoing rejections, assertions and official notices are traversed by the instant response.35 USC 102 It is well settled law that anticipation requires that each and every element as set forth in the claim is found, either expressly or inherently described, in a single prior art reference. See Verdegaal Bros. v. Union Oil Co. of California, 814 F.2d 628, 631 (Fed. Cir. 1987). The identical invention must be shown in as complete detail as is contained in the claim. See Richardson v. Suzuki Motor Co.,  868  F.2d  1226,  1236  (Fed. Cir.  1989).The Foutch reference fails to disclose a hybrid electric gas turbine engine two speed transmission for a low spool drive comprising: an accessory gearbox in operative communication with a low speed spool motor- generator; a transmission in operative communication with the accessory gearbox and the low speed spool motor- generator, wherein the transmission comprises a two speed transmission configured for hybrid electric low spool drive applications, the two speed transmission comprises clutch packs and an epicyclic geartrain configured to reduce a speed range at the low speed spool motor-generator; a low speed spool angled gearbox in operative communication with the transmission; and a low speed spool in operative communication with the low speed spool angled gearbox, as claimed in claim 1. The Foutch reference fails to disclose each and every claimed element as claimed in claims 8 and 14 as well.The Foutch reference merely discloses at col. 4 to col. 5 turbine engine 110 with a system 140 for providing mechanical power to an aircraft accessory 142 a-c with the turbine engine 110, according to an example implementation.The turbine engine 110 includes the low-speed spool 122 and the high-speed spool 120 as described above in FIG. 2 . In FIG. 3 , a low-speed spool drive shaft 144 and a high-speed spool drive shaft 146 are shown. The system 140 includes an accessory gearbox 148 disposed between the low-speed spool 122 and the high-speed spool 120, and the accessory gearbox 148 is configured to drive the aircraft accessory 142 a-c.The system 140 also includes a clutch 150 disposed within the accessory gearbox 148, and the clutch 150 is configured to enable either the high-speed spool 120 or the low-speed spool 122 to provide mechanical power to the aircraft accessory 142 a-b via the accessory gearbox 148.A first gear train 160 and a second gear train 162, and the first gear train 160 is coupled to a first shaft 164 of the clutch 150 and the first gear train 160 is driven by the high-speed spool drive shaft 146. The second gear train 162 is coupled to a second shaft 166 of the clutch 150 and the second gear train 162 is driven by the low-speed spool drive shaft 144. Foutch at col. 8 merely discloses Tables 1 and 2 below show example methods of aligning the system 140 shown in FIGS. 9-10 during different phases of flight and for different failure modes for operation of the system 140 in any of the modes as described with reference to FIGS.11-14.However, the Foutch reference fails to disclose a transmission in operative communication with the low speed spool angled gearbox, wherein the transmission comprises a two speed transmission configured for hybrid electric low spool drive applications, the two speed transmission comprises clutch packs and an epicyclic geartrain configured to reduce a speed range at the low speed spool motor-generator, as claimed.The Office Action includes the erroneous assertion that Foutch discloses a two speed transmission at Tables 1- 2 which document multiple modes of the clutch position and different modes of operation of the aircraft engine.However, there is no disclosure of a two speed transmission, let alone a two speed transmission configured for hybrid electric low spool drive applications, the two speed transmission comprises clutch packs and an epicyclic geartrain configured to reduce a speed range at the low speed spool motor-generator, as claimed.The modes labeled in the Tables, are described for failure modes for operation of the system 140. Such as when there is a failure in the system for supplying power via the low speed spool, such as a failure of the power transfer unit 173. The Tables describe different phases of flight. The Tables describe the position of the clutch as open or closed. The Tables describe the power source for aircraft accessories. The Tables never disclose a two speed transmission.Since the Foutch reference fails to disclose each and every claimed element, as claimed, then there is no anticipation. Withdrawal of the anticipation is respectfully requested.35 USC 103 In order to establish a prima facie case of obviousness, each and every claimed element must be taught in the prior art.The combination of Foutch/APA/Joensson/Muldoon references fails to teach or suggest each and every claimed element as claimed in claims 1, 8 and 14.It has already been shown above that the Foutch reference fails to disclose all of the claimed elements in the independent claims 1, 8, and 14.The combination of Foutch/APA/Joensson/Muldoon does not remedy the defects of Foutch.Since the combination of references fails to disclose each and every claimed element, as claimed, then there is no prima face case of obviousness. Withdrawal of the obviousness rejection is respectfully requested.For these reasons, claim 1 is not rendered obvious.Claims 2-5 and 7 are allowable for the same reasons as claim 1 as well as on their own accord. Claim 8 is not rendered obvious. Claims 9-10 and 12-13 are allowable for the same reasons as claim 8 as well as on their own accord.Claim 14 is not rendered obvious. Claims 15 and 17-20 are allowable for the same reasons as claim 14 as well as on their own accord. For the foregoing reasons, the instant application is believed to be in condition for allowance.Such allowance is respectfully solicited.Should the Examiner believe an additional amendment is needed to place the case in condition for allowance, the Examiner is hereby invited to contact Applicant's attorney.No fee is due as a result of the instant response.Should the Director determine that an additional fee is due, he is hereby authorized to charge said fee to said Deposit Account No. 21-0279.Respectfully submitted, Thomas E. Clark et al.By /Andrew D. Gathy #46441/ Andrew D. Gathy BACHMAN & LaPOINTE, P.C.Reg. No. 46,441 Attorney for Applicant Telephone:(203)777-6628 ext. 116 Telefax:  (203)865-0297 Email: doc-eoac a. c m Date: July 2, 2025


CITED REFERENCE SUMMARIES: Ref WO2008082335: Claims:
A power transmission device (2) for a gas turbine engine (1) comprising a low pressure shaft (11), a high pressure shaft (10) , wherein the high pressure shaft (10) is arranged concentric to the low pressure shaft (11) , and an accessory unit (12) comprising at least one electric machine (29,30) adapted for a gas turbine engine starting operation and/or for generating electrical power, characterized in that the power transmission device (2) comprises a transmission unit (13) operatively connected to the low pressure shaft (11) and adapted for power transmission from the low pressure shaft (11) to the accessory unit (12), that the transmission unit (13) is positioned non-concentric with the low pressure shaft (11) , that a first transmission means (18) is operatively connected for power transmission from the low pressure shaft (11) to the transmission unit (13), and that a second transmission means (32) is operatively connected for power transmission from the accessory unit (12) to the high pressure shaft in a manner bypassing the transmission unit (13) . 2. A power transmission device according to claim 1 or 2, characterized in that the transmission unit (13) is arranged externally of a gas turbine engine housing (15) , which accommodates at least part of the low pressure shaft (11) . 3. A power transmission device according to claim 1 or 2, characterized in that the first transmission means (18) comprises a first tower shaft (19) . 4. A gas turbine engine according to any preceding claim, characterized in that the second transmission means (32) comprises a second tower shaft (38) . 5. A power transmission device according to any preceding claim, characterized in that it comprises means (16) for operatively connecting and disconnecting, respectively at least one of said electric machines (29,30) adapted for the gas turbine engine starting operation to the high pressure shaft (10) . 6. A power transmission device according to claim 5, characterized in that the connection means (16) is adapted to automatically disconnect said at least one electric machine (29,30) from operational connection with the high pressure shaft (10) when a speed of the high pressure shaft exceeds a predetermined limit value. 7. A power transmission device according to claim 6, characterized in that the predetermined limit value corresponds to a maximum speed for a gas turbine engine starting operation. 8. A power transmission device according to any one of claims 5-7, characterized in that the connection means (16) comprises a clutch. 9. A power transmission device according to claim 8, characterized in that the high pressure shaft clutch (16) is formed by a freewheel mechanism. 10. A power transmission device according to any one of claims 5-9, characterized in that the connection means (16) is arranged non-concentric with the high pressure shaft (10) . 11. A power transmission device according to any one of claims 5-10, characterized in that the connection means (16) is arranged externally of a gas turbine engine housing (15) , which accommodates at least part of the high pressure shaft (10) . 12. A power transmission device according to any one of claims 5-11, characterized in that accessory unit (12) comprises the connection means (16) . 13. A power transmission device according to any preceding claim, characterized in that the second transmission means (32) is operatively connected for power transmission from at least one of said electric machines (29,30) adapted for the gas turbine engine starting operation to the high pressure shaft (10) and also for power transmission from the high pressure shaft (10) to the accessory unit (12) . 14. A power transmission device according to one of claims 5-12 and claim 13, characterized in that at least one power consumer (33,36) in the accessory unit (12) is arranged between the connection means (16) and the high pressure shaft (10) in the power transmission path between said electric machine (29,30) adapted for the gas turbine engine starting operation and the high pressure shaft (10) . 15. A power transmission device according to any preceding claim, characterized in that the accessory unit (12) is arranged externally of a gas turbine engine housing (15) , which accommodates at least part of the high pressure shaft (10) . 16. A power transmission device according to any preceding claim, characterized in that the transmission unit (13) is adapted to transmit at least 50% of the required power for the power consumers in the accessory unit from the low pressure shaft (11) . 17. A power transmission device according to any preceding claim, characterized in that the transmission unit (13) comprises a gear changing mechanism (14) adapted to change between at least two gears for said power transmission from the low pressure shaft (11) to the accessory unit (12) . 18. A power transmission device according to claim 17, characterized in that the transmission unit (12) comprises a gear set (21) and that the gear changing mechanism (14) is adapted for connecting and disconnecting, respectively, the gear set (21) from being drivingly connected to the accessory unit (12) . 19. A power transmission device according to claim 18, characterized in that the gear set (21) is arranged on an intermediate power transmission shaft (17) in the transmission unit (13), and that the gear changing mechanism (14) is arranged in direct contact with the intermediate power transmission shaft (17) . 20. A power transmission device according to claim 18 or 19, characterized in that the gear changing mechanism (14) comprises a clutch. 21. A power transmission device according to any one of claims 18-20, characterized in that the gear set (21) is a differential gear. 22. A gas turbine engine (1), characterized in that it comprises a power transmission device (2) according to any preceding claim. 23. An aeroplane characterized in that it comprises a gas turbine engine (1) according to claim 22.
A power transmission device (2) for a gas turbine engine (1) comprising a low pressure shaft (11), a high pressure shaft (10) , wherein the high pressure shaft (10) is arranged concentric to the low pressure shaft (11) , and an accessory unit (12) comprising at least one electric machine (29,30) adapted for a gas turbine engine starting operation and/or for generating electrical power, characterized in that the power transmission device (2) comprises a transmission unit (13) operatively connected to the low pressure shaft (11) and adapted for power transmission from the low pressure shaft (11) to the accessory unit (12), that the transmission unit (13) is positioned non-concentric with the low pressure shaft (11) , that a first transmission means (18) is operatively connected for power transmission from the low pressure shaft (11) to the transmission unit (13), and that a second transmission means (32) is operatively connected for power transmission from the accessory unit (12) to the high pressure shaft in a manner bypassing the transmission unit (13) .
A power transmission device according to claim 1 or 2, characterized in that the transmission unit (13) is arranged externally of a gas turbine engine housing (15) , which accommodates at least part of the low pressure shaft (11) .
A power transmission device according to claim 1 or 2, characterized in that the first transmission means (18) comprises a first tower shaft (19) .
A gas turbine engine according to any preceding claim, characterized in that the second transmission means (32) comprises a second tower shaft (38) .
A power transmission device according to any preceding claim, characterized in that it comprises means (16) for operatively connecting and disconnecting, respectively at least one of said electric machines (29,30) adapted for the gas turbine engine starting operation to the high pressure shaft (10) .
A power transmission device according to claim 5, characterized in that the connection means (16) is adapted to automatically disconnect said at least one electric machine (29,30) from operational connection with the high pressure shaft (10) when a speed of the high pressure shaft exceeds a predetermined limit value.
A power transmission device according to claim 6, characterized in that the predetermined limit value corresponds to a maximum speed for a gas turbine engine starting operation.
A power transmission device according to any one of claims 5-7, characterized in that the connection means (16) comprises a clutch.
A power transmission device according to claim 8, characterized in that the high pressure shaft clutch (16) is formed by a freewheel mechanism.
A power transmission device according to any one of claims 5-9, characterized in that the connection means (16) is arranged non-concentric with the high pressure shaft (10) .
A power transmission device according to any one of claims 5-10, characterized in that the connection means (16) is arranged externally of a gas turbine engine housing (15) , which accommodates at least part of the high pressure shaft (10) .
A power transmission device according to any one of claims 5-11, characterized in that accessory unit (12) comprises the connection means (16) .
A power transmission device according to any preceding claim, characterized in that the second transmission means (32) is operatively connected for power transmission from at least one of said electric machines (29,30) adapted for the gas turbine engine starting operation to the high pressure shaft (10) and also for power transmission from the high pressure shaft (10) to the accessory unit (12) .
A power transmission device according to one of claims 5-12 and claim 13, characterized in that at least one power consumer (33,36) in the accessory unit (12) is arranged between the connection means (16) and the high pressure shaft (10) in the power transmission path between said electric machine (29,30) adapted for the gas turbine engine starting operation and the high pressure shaft (10) .
A power transmission device according to any preceding claim, characterized in that the accessory unit (12) is arranged externally of a gas turbine engine housing (15) , which accommodates at least part of the high pressure shaft (10) .
A power transmission device according to any preceding claim, characterized in that the transmission unit (13) is adapted to transmit at least 50% of the required power for the power consumers in the accessory unit from the low pressure shaft (11) .
A power transmission device according to any preceding claim, characterized in that the transmission unit (13) comprises a gear changing mechanism (14) adapted to change between at least two gears for said power transmission from the low pressure shaft (11) to the accessory unit (12) .
A power transmission device according to claim 17, characterized in that the transmission unit (12) comprises a gear set (21) and that the gear changing mechanism (14) is adapted for connecting and disconnecting, respectively, the gear set (21) from being drivingly connected to the accessory unit (12) .
A power transmission device according to claim 18, characterized in that the gear set (21) is arranged on an intermediate power transmission shaft (17) in the transmission unit (13), and that the gear changing mechanism (14) is arranged in direct contact with the intermediate power transmission shaft (17) .
A power transmission device according to claim 18 or 19, characterized in that the gear changing mechanism (14) comprises a clutch.
A power transmission device according to any one of claims 18-20, characterized in that the gear set (21) is a differential gear.
A gas turbine engine (1), characterized in that it comprises a power transmission device (2) according to any preceding claim.
An aeroplane characterized in that it comprises a gas turbine engine (1) according to claim 22.