{"id":"F2007L03531","name":"AD/ENST 28/40 - Main Rotor Push Pull Rod","slug":"ad-enst-28-40-main-rotor-push-pull-rod","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":69787,"registerId":"commonwealth-F2007L03531-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Enstrom F-28 Series Helicopters","sectionType":"division","heading":"Enstrom F-28 Series Helicopters","content":"### Enstrom F-28 Series Helicopters\n\n| AD/ENST 28/40 | Main Rotor Push Pull Rod | 11/2007 DM |\n| ------------- | ------------------------ | ---------- |\n\n```html\n

Applicability:

Enstrom Helicopter Company Model F-28A, F-28C, and F-28F helicopters, excluding serial number (S/N) 816 and subsequent; Model 280, 280C, 280F, and 280FX helicopters, excluding S/N 2100 and subsequent; and Model TH-28, 480, and 480B helicopters, excluding S/N 5058 and subsequent.

Requirement:

1. Review the helicopter maintenance records and determine the date that each push-pull rod, part number (P/N) 28-16253 - all dash numbers (for Model F-28A, F- 28C, F-28F, 280, 280C, 280F, and 280FX helicopters) and P/N 4140532 - all dash numbers (for Model TH-28, 480, and 480B helicopters), was installed. If the date cannot be determined from the maintenance records, use the ``Date MFD'', which is located on the helicopter data plate, as the installation date for the push- pull rod.

2. For Model F-28A, F-28C, F-28F, 280, 280C, 280F, and 280FX helicopters, visually inspect the exterior and interior of each of the three push-pull rods for corrosion severe enough to cause pitting or any moisture, paying special attention to the area of the lower fitting, in accordance with section 5.1., INSPECTION, in Enstrom Helicopter Corporation Service Directive Bulletin No. 0096, dated 10 September 2003 (SDB 0096).

Table 1

Helicopter models

Push-pull rod service life

Compliance times

Model F-28A, F-28C, F-28F, 280, 280C, 280F, and 280FX helicopters.

Push-pull rod that has been installed for 20 or more years.

Inspect within 10 hours time-in-service (TIS) or at next annual inspection, whichever occurs first.

Model F-28A, F-28C, F-28F, 280, 280C, 280F, and 280FX helicopters.

Push-pull rod that has been installed for 10 or more years, but less than 20 years.

Inspect within 50 hours TIS or at the next annual inspection, whichever occurs first.

Model F-28A, F-28C, F-28F, 280, 280C, 280F, and 280FX helicopters.

Push-pull rod that has been installed for less than 10 years.

Inspect before the service life of the push-pull rod reaches 10 years since initial installation.

a) If corrosion without pitting is found on a push-pull rod, then repair, reassemble, remark, and reinstall it in accordance with section 5.2., REPAIR/REASSEMBLY, in SDB 0096.

b) If corrosion is found that is severe enough to cause pitting, or if any moisture is visible on the inside of a push-pull rod, replace it with an airworthy push-pull rod.

Note 1: Determining continued serviceability of the push-pull rods by inspecting the exterior only of each push-pull rod is described in Enstrom Helicopter Corporation Service Information Letter No. 0156, dated 9 December 2003.

3. For Model TH-28, 480 and 480B helicopters, visually inspect the exterior and interior of each of the three push-pull rods for corrosion severe enough to cause pitting or any moisture, paying special attention to the area of the lower fitting, in accordance with section 5.1., INSPECTION, in Enstrom Helicopter Corporation Service Directive Bulletin No. T-019, dated 10 September 2003 (SDB T-019).

Table 2

Helicopter models

Push-pull rod service life

Compliance times

Model TH-28, 480, and 480B helicopters.

Push-pull rod that has been installed for 10 or more years.

Inspect within 50 hours TIS or at the next annual inspection, whichever occurs first.

Model TH-28, 480, and 480B helicopters.

Push-pull rod that has been installed for less than 10 years.

Inspect before the service life of the push-pull rod reaches 10 years since initial installation.

a) If corrosion without pitting is found on a push-pull rod, then repair, reassemble, remark, and reinstall it in accordance with section 5.2., REPAIR/REASSEMBLY, in SDB T-019.

b) If corrosion is found that is severe enough to cause pitting, or if any moisture is visible on the inside of a push-pull rod, replace it with an airworthy push-pull rod.

Note 2: Determining continued serviceability of the push-pull rods by inspecting the exterior only of each push-pull rod is described in Enstrom Helicopter Corporation Service Information Letter No. T-019.

Note 3: FAA AD 2007-11-02 Amdt 39-15059 dated 5 July 2007 refers.

\n```\n\n| Compliance: | 1. Within 10 hours time-in-service (TIS) or at the next annual inspection, whichever occurs first after the effective date of this AD.2. In accordance with the compliance times stated in Table 1 of this AD.a) Before further flight, after the effective date of this AD.b) Before further flight, after the effective date of this AD.3. In accordance with the compliance times stated in Table 2 of this AD.a) Before further flight, after the effective date of this AD.b) Before further flight, after the effective date of this AD. |\n| ----------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |\n| | This Airworthiness Directive becomes effective on 2 October 2007. |\n| Background: | This AD requires the determining of the installation dates for each main rotor push-pull control rod (push-pull rod), inspecting the push-pull rods for corrosion, replacing any push-pull rod which has corrosion that is severe enough to cause pitting, or has visible moisture inside the rod, and repairing each push-pull rod that has corrosion but no pitting. This is prompted by one reported incident in which the helicopter pilot encountered severe in-flight vibration due to the failure of a push-pull rod, requiring an emergency landing. The actions specified by this AD are intended to detect corrosion and prevent failure of a push-pull rod, and subsequent loss of control of the helicopter. |\n\n![](image.001.png) \nCharles Lenarcic \nDelegate of the Civil Aviation Safety Authority\n\n30 August 2007","sortOrder":0},{"sectionNumber":"AD/ENST 28/40","sectionType":"part","heading":"AD/ENST 28/40","content":"## AD/ENST 28/40","sortOrder":1},{"sectionNumber":"Main Rotor Push Pull Rod","sectionType":"part","heading":"Main Rotor Push Pull Rod","content":"## Main Rotor Push Pull Rod","sortOrder":2},{"sectionNumber":"11/2007 DM","sectionType":"part","heading":"11/2007 DM","content":"## 11/2007 DM","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":5,"scope_assessment":{"changed":false,"description":"The AD sets a defined applicability: specified Enstrom F‑28, 280 and TH‑28/480 models, excluding listed serial numbers. The text does not indicate any alteration of that applicability beyond the serial‑number exclusions stated in the Applicability section."},"complexity_factors":["Multiple affected models with serial‑number exclusions create targeted applicability (Applicability table).","Requirement to determine installation date from maintenance records or use ‘Date MFD’ if unknown (Requirement 1) increases record‑checking burden.","Different compliance windows depending on model and push‑pull rod service life (Table 1 and Table 2) — immediate (10 TIS), short (50 TIS) or before 10‑year service life.","Inspections must examine both exterior and interior and focus on lower fitting areas (Requirement 2 and 3; section 5.1 in SDB 0096 and SDB T‑019) — interior access raises labour/time costs.","Different corrective actions based on findings: repair/reassemble/remark per SDB 0096/T‑019 for corrosion without pitting (section 5.2), versus mandatory replacement if pitting or internal moisture is present.","Cross‑references to manufacturer Service Directive Bulletins (SDB 0096 and SDB T‑019) and Service Information Letters add procedural dependencies and potential for interpretive discretion by maintenance staff.","Three push‑pull rods per helicopter must each be inspected, multiplying inspection and potential replacement costs.","Immediate safety‑critical compliance (some actions before further flight) increases scheduling and operational disruption risk."],"plain_english_summary":"This Airworthiness Directive requires owners/operators of specified Enstrom F‑28, 280 and TH‑28/480 series helicopters (with listed serial‑number exclusions) to determine each main rotor push‑pull rod’s installation date and visually inspect all three rods (interior and exterior) for corrosion, pitting or internal moisture. Corrosion without pitting must be repaired per Enstrom service bulletins; rods with pitting or internal moisture must be replaced. Compliance times depend on model and rod age, with some inspections due within 10 flight hours or at the next annual inspection. Owners/operators pay for inspections and any repairs or replacements."},"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"This is a standard Airworthiness Directive issued in response to a specific safety incident. The scope remains tightly focused on the original safety issue: preventing push-pull rod failures due to internal corrosion in Enstrom helicopters. No scope creep is evident."},"complexity_factors":["Multiple helicopter model groups with different part numbers and service bulletins (SDB 0096 vs SDB T-019)","Tiered compliance schedule based on component age (three different timeframes for F-28 series, two for TH-28/480 series)","Cross-references to external manufacturer documents (Service Directive Bulletins) that are not reproduced in the AD itself","Conditional logic for repair vs replacement based on inspection findings (pitting vs non-pitting corrosion)","Serial number exclusions creating applicability exceptions (S/N 816+, 2100+, 5058+ excluded)","Alternative compliance methods referenced in notes (exterior-only inspection per Service Information Letters)"],"plain_english_summary":"This AD requires owners/operators of specified Enstrom helicopters to inspect main rotor push‑pull rods for internal moisture and corrosion (which can be hidden) and to repair or replace rods as necessary to prevent sudden failure and loss of control. Compliance times are set based on rod age (sooner for older installations). It responds to an in‑service failure and ensures records or manufacture dates establish service life for required actions."},"flash_summary_failed":{"failed":true,"reason":"A positive credit balance is required for all requests, including BYOK, so fallback providers remain available. Add credits at https://vercel.com/d?to=%2F%5Bteam%5D%2F%7E%2Fai%3Fmodal%3Dtop-up to continue.","source":"analysis-cron"}},"importantCases":[],"_links":{"self":"/api/acts/ad-enst-28-40-main-rotor-push-pull-rod","history":"/api/acts/ad-enst-28-40-main-rotor-push-pull-rod/history","analysis":"/api/acts/ad-enst-28-40-main-rotor-push-pull-rod/analysis","conflicts":"/api/acts/ad-enst-28-40-main-rotor-push-pull-rod/conflicts","importantCases":"/api/acts/ad-enst-28-40-main-rotor-push-pull-rod/important-cases","documents":"/api/acts/ad-enst-28-40-main-rotor-push-pull-rod/documents"}}