{"id":"F2005L01063","name":"AD/CT58/19 - Stage 1 Compressor Disks","slug":"ad-ct58-19-stage-1-compressor-disks","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":34678,"registerId":"commonwealth-F2005L01063-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"General Electric Turbine Engines - CT58 ","sectionType":"division","heading":"General Electric Turbine Engines - CT58 Series","content":"### General Electric Turbine Engines - CT58 Series\n\n| AD/CT58/19 | Stage 1 Compressor Disks | 6/2005 |\n| ---------- | ------------------------ | ------ |\n\n```html\n

Applicability:

General Electric Company (GE) CT58-140-1, CT58-140-2, and surplus military T58-GE-5, -10, -100, and -402 turboshaft engines with stage 1 compressor disks, part number (P/N) 5001T20P01, that have a serial number (SN) listed in Table 1 of this Directive:

Table 1-Stage 1 Compressor Disk SNs Affected By This Directive

GATD0PD2

GATH5T76

GATH6CE5

GATH6T01

GATH7KH0

GATD0PD3

GATH5T77

GATH6CE6

GATH6T02

GATH7KH1

GATD0PD5

GATH5T78

GATH6CE7

GATH6T03

GATH7KH2

GATD0PD6

GATH5T79

GATH6CE8

GATH6T04

GATH7LAL

GATD0PD7

GATH5T7A

GATH6CE9

GATH6T05

GATH7LAM

GATD0PD8

GATH5T7C

GATH6CEA

GATH7K4K

GATH7LAN

GATD0PD9

GATH5T7D

GATH6CEC

GATH7K4L

GATH7LAP

GATD0PDA

GATH5T7E

GATH6CED

GATH7K4M

GATH7LAR

GATD0PDC

GATH5T7F

GATH6CEE

GATH7K4N

GATH7LAT

GATH53GC

GATH5T7G

GATH6CEF

GATH7K4P

GATH7LAW

GATH53GD

GATH5T7H

GATH6RH8

GATH7K4R

GATH7LC0

GATH53GE

GATH6CDL

GATH6RH9

GATH7K4T

GATH7LC1

GATH53GF

GATH6CDM

GATH6RHC

GATH7K5G

GATH7LC2

GATH53GH

GATH6CDN

GATH6RHD

GATH7KGH

GATH7LC3

GATH53GJ

GATH6CDP

GATH6RHE

GATH7KGK

GATH7LC4

\n```\n\n```html\n

GATH53GK

GATH6CDR

GATH6RHF

GATH7KGL

GATH7LC5

GATH5T70

GATH6CDT

GATH6RHG

GATH7KGM

GATH7LC6

GATH5T71

GATH6CE0

GATH6RHH

GATH7KGN

GATH7LC7

GATH5T72

GATH6CE1

GATH6RHJ

GATH7KGP

GATH7LC8

GATH5T73

GATH6CE2

GATH6RWT

GATH7KGR

GATH7M8G

GATH5T74

GATH6CE3

GATH6RWW

GATH7KGT

GATH7M8H

GATH5T75

GATH6CE4

GATH6T00

GATH7KGW

GATH7M8J

GATH7M8K

GATH7PRT

GATH86K4

GATH8HGM

GATH8WD6

GATH7M8L

GATH7PRW

GATH86K5

GATH8HGN

GATH8WD7

GATH7M8M

GATH7PT0

GATH8A5G

GATH8HGP

GATH8WD8

GATH7M8N

GATH7RTP

GATH8A5H

GATH8HGR

GATH8WD9

GATH7MLK

GATH7RTR

GATH8A5J

GATH8HGT

GATH8WDA

GATH7MLL

GATH7RTT

GATH8A5K

GATH8HGW

GATH8WDC

GATH7MLM

GATH82R8

GATH8A5L

GATH8HH0

GATH8WDD

GATH7MLN

GATH82R9

GATH8A5M

GATH8HH1

GATH8WDE

GATH7MLP

GATH82RA

GATH8A5N

GATH8HH2

GATH8WDF

GATH7MLR

GATH82RD

GATH8A5P

GATH8HH3

GATH8WDG

GATH7MLT

GATH82RE

GATH8A5T

GATH8HH4

GATH8WDH

GATH7MLW

GATH82RF

GATH8A5W

GATH8HH5

GATH8WDJ

GATH7MM0

GATH82RG

GATH8A60

GATH8HH6

GATH8WDK

GATH7MM1

GATH82RH

GATH8A61

GATH8HH7

GATH8WDL

GATH7MM2

GATH82RJ

GATH8A62

GATH8K0H

GATH94R3

\n```\n\n```html\n

GATH7MM3

GATH82RK

GATH8A63

GATH8K0J

GATH94R4

GATH7PPT

GATH82RL

GATH8A64

GATH8K0K

GATH94R6

GATH7PPW

GATH82RM

GATH8A66

GATH8K0L

GATH94R7

GATH7PR0

GATH82RN

GATH8A67

GATH8K0M

GATH94R8

GATH7PR1

GATH82RP

GATH8A68

GATH8K0N

GATH94R9

GATH7PR2

GATH82RR

GATH8GRG

GATH8K0P

GATH94RA

GATH7PR3

GATH82RT

GATH8GRH

GATH8K0R

GATH94RC

GATH7PR4

GATH82RW

GATH8GRK

GATH8K0T

GATH94RD

GATH7PR5

GATH82T0

GATH8GRL

GATH8K0W

GATH94RE

GATH7PR6

GATH82T1

GATH8GRM

GATH8K12

GATH94RF

GATH7PR7

GATH86JD

GATH8GRN

GATH8K13

GATH94RG

GATH7PR8

GATH86JE

GATH8GRP

GATH8K14

GATH94RJ

GATH7PR9

GATH86JF

GATH8GRR

GATH8K15

GATH94RK

GATH7PRA

GATH86JG

GATH8GRT

GATH8K16

GATH94RN

GATH7PRC

GATH86JH

GATH8GRW

GATH8K17

GATH94RP

GATH7PRD

GATH86JJ

GATH8GT0

GATH8K18

GATH94RR

GATH7PRE

GATH86JK

GATH8GT1

GATH8K19

GATH94RT

GATH7PRF

GATH86JL

GATH8GT3

GATH8W7H

GATH96HF

GATH7PRG

GATH86JM

GATH8GT5

GATH8W7J

GATH96HG

GATH7PRH

GATH86JN

GATH8GT7

GATH8W7L

GATH96HK

GATH7PRJ

GATH86JP

GATH8GT8

GATH8W7M

GATH96HL

GATH7PRK

GATH86JR

GATH8HGF

GATH8W7N

GATH96HM

\n```\n\n```html\n

GATH7PRL

GATH86JT

GATH8HGG

GATH8W7P

GATH96HN

GATH7PRM

GATH86JW

GATH8HGH

GATH8W7R

GATH96HR

GATH7PRN

GATH86K0

GATH8HGJ

GATH8W7T

GATH96HT

GATH7PRP

GATH86K2

GATH8HGK

GATH8WD4

GATH96HW

GATH7PRR

GATH86K3

GATH8HGL

GATH8WD5

GATH96J0

Note 1: These engines are installed on, but not limited to, Agusta S.p.A AS-61N, AS-61N1, Sikorsky S-61L, S-61N, S-61R, and S-61NM helicopters, and the following surplus military helicopters: Sikorsky S-61D and S-61V, Glacier CH-3E, Siller CH-3E and SH-3A, and Robinson Crane CH-3C, CH-3E, HH-3C, HH-3E, and Carson
S-61L helicopters.

Requirement:

1. Replace the stage 1 compressor disk.

Note 2: GE Alert Service Bulletin (ASB) No. CT58 S/B 72-A0196, dated 24 July 2003, contains information on replacing the stage 1 compressor disk.

2. Do not install any stage 1 compressor disk, P/N 5001T20P01, that has a SN listed in Table 1 of this Directive and has 2,100 hours TSN or more, into any engine.

Note 3: FAA AD 2005-04-10 Amdt 39-13982 refers.

Compliance:

1. At or before reaching a reduced low-cycle fatigue (LCF) life limit of 2,100 hours time-since-new (TSN) or by 31 December, 2008, whichever occurs first.

2. After the effective date of this AD.

This Airworthiness Directive becomes effective on 9 June 2005.

Background:

This Directive requires removing certain stage 1 compressor disks from service before reaching a reduced LCF life limit for those affected disks. This Directive results from two reports of low blade tip clearances in the compressor. The requirements of this Directive are to prevent LCF cracking and failure of the stage 1 compressor disk, an uncontained engine failure, and damage to the helicopter.

\n```\n\n![](image.001.png) \nJames Coyne \nDelegate of the Civil Aviation Safety Authority\n\n28 April 2005","sortOrder":0},{"sectionNumber":"AD/CT58/19","sectionType":"part","heading":"AD/CT58/19","content":"## AD/CT58/19","sortOrder":1},{"sectionNumber":"Stage 1 Compressor Disks","sectionType":"part","heading":"Stage 1 Compressor Disks","content":"## Stage 1 Compressor Disks","sortOrder":2},{"sectionNumber":"6/2005","sectionType":"part","heading":"6/2005","content":"## 6/2005","sortOrder":3}],"analysis":{"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The Directive's scope matches its stated objective in the text: it targets specific CT58 engine models and only stage 1 compressor disks with serial numbers listed in Table 1, requiring replacement before the reduced LCF life limit or by a set date to prevent LCF cracking and uncontained failure (Applicability; Requirement; Compliance; Background). It does not expand to other parts, models or broader operational restrictions."},"complexity_factors":["Long, explicit list of affected serial numbers (Table 1) — identification burden for operators/maintenance records","Technical criterion expressed as a reduced low‑cycle fatigue life limit: 2,100 hours TSN (Compliance para 1)","Dual compliance deadline: reach life limit or fixed calendar date (Compliance para 1)","Simple mandatory actions: replace disk and ban installation of listed disks at/above threshold (Requirement para 1–2)","Cross‑reference to manufacturer service bulletin and FAA AD (Notes) — additional documents to consult for procedure details"],"plain_english_summary":"This Airworthiness Directive requires owners/operators of GE CT58 series engines with stage 1 compressor disk P/N 5001T20P01 (serial numbers listed in Table 1) to replace those disks and forbids installing any listed disk that has 2,100 hours TSN or more. (Requirement; Table 1)\n\nOperators must comply by 2,100 hours time‑since‑new or by 31 December 2008, whichever is earlier, and bear the replacement cost. The Directive states its purpose is to prevent low‑cycle‑fatigue cracking and uncontained engine failure. (Compliance; Background)"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific mechanical defect in specific engine serial numbers. The scope remains precisely limited to the identified low-cycle fatigue risk in stage 1 compressor disks. There is no evidence of scope creep; the directive maintains its original narrow technical purpose throughout."},"complexity_factors":["Highly specific technical scope targeting one specific part (P/N 5001T20P01) across specific engine models","Extensive tabular data: over 200 individual serial numbers listed across multiple HTML tables requiring cross-referencing","Dual compliance structure with two distinct requirements (replacement vs. installation prohibition)","Time-based compliance with 'whichever occurs first' conditional logic (2,100 hours TSN vs. 31 December 2008)","Reference to external technical document (GE Alert Service Bulletin CT58 S/B 72-A0196) for implementation details","Cross-reference to FAA AD 2005-04-10 indicating harmonisation with US aviation safety regulations","No defined terms section or interpretation provisions — relies entirely on technical aviation terminology"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — a legally binding safety order issued by the Civil Aviation Safety Authority (CASA) that mandates specific maintenance actions on aircraft engines.\n\n**What it does:**\nThis directive requires owners and operators of certain General Electric CT58 turboshaft engines to **replace specific stage 1 compressor disks** before they reach 2,100 flight hours of use. It also prohibits installing any of these specific disks into engines if they already have 2,100 or more hours on them.\n\n**Who it affects:**\n- Operators of helicopters using GE CT58-140-1, CT58-140-2, and surplus military T58-GE-5, -10, -100, and -402 engines\n- Specifically, engines with stage 1 compressor disks bearing part number **5001T20P01** and serial numbers listed in the directive's tables (over 200 individual serial numbers)\n- Common helicopter models affected include Agusta AS-61N variants, Sikorsky S-61 series, and various military surplus helicopters converted for civilian use\n\n**Why it matters:**\nThe directive addresses a serious safety risk. Two reports of low blade tip clearances in the compressor indicated potential **low-cycle fatigue (LCF)** problems. If the disk fails due to fatigue cracking, it could cause an **uncontained engine failure** — where engine parts break through the engine casing and potentially strike the helicopter or its occupants. This directive prevents catastrophic engine failure and potential loss of life.\n\n**Key deadlines:**\n- Replacement required by **31 December 2008** or before reaching 2,100 hours time-since-new (TSN), whichever comes first\n- The prohibition on installing high-time disks takes effect immediately upon the directive becoming active\n- The directive became effective on **9 June 2005**"}},"importantCases":[],"_links":{"self":"/api/acts/ad-ct58-19-stage-1-compressor-disks","history":"/api/acts/ad-ct58-19-stage-1-compressor-disks/history","analysis":"/api/acts/ad-ct58-19-stage-1-compressor-disks/analysis","conflicts":"/api/acts/ad-ct58-19-stage-1-compressor-disks/conflicts","importantCases":"/api/acts/ad-ct58-19-stage-1-compressor-disks/important-cases","documents":"/api/acts/ad-ct58-19-stage-1-compressor-disks/documents"}}