**Ref No.: AOT-CN235-57-0001** 

**Rev No.: 1**  **Rev Date:**  **14/03/2014**

SERVICES DIRECTORATE Po John Lennon s/n
28906 Getafe, Madrid, SPAIN **MTA.TechnicalService@military.airbus.com** 

# Alert Operators Transmission **Page 1/11** 
ATA Chapter: **57** Subject: **Inspection of Aileron Control Rod Fittings**

Aircraft Type: **CN-235**
Applicability: **All CN-235**

Limited Distribution: **N/A**

Referenced Documents:
**Ref.1: IPC 57-61-19-001-01-01 - Item 170**
**Ref.2: IPC 57-61-19-001-01-01 - Item 180 Ref.3: AMM 57-61-11 – Aileron Removal/Installation** 



### 1. REASON FOR REVISION

**Rev No.1: Correction of typing error in Annex 1- Pa ragraph 4.C.** 



### 2. REASON

**2.1 FACTS** 

**One CN-235 Operator recently reported cases of crac ks on the control rod fittings (inboard and outboar**  **d) of the ailerons (RH & LH side) of two aircraft. These find**  **ings were detected during scheduled maintenance tas ks.** 

**The cracks are located on the lugs of the control r od fittings (see Ref.1 and Ref.2). At the time of f**  **inding the two aircraft had accumulated between 16000 and 17000 Flight Hour**  **s (FH), around 6000 Flight Cycles (FC) and 20 years in service.** 

**2.2 CONSEQUENCES** 

**If the failure of a control rod fitting (inboard or outboard) does not cause aileron jamming, the oper**  **ation of the affected**

**aileron can still be ensured with the other control rod.** 

**In case of jamming of the affected aileron, the UNT IE of FLT CONT DISC ROLL switch would allow the cre**  **w to control the other operative aileron.** 

**2.3 AIM** 

**The aim of this AOT is to verify the integrity of t he control rod fittings by means of a onetime Non-D**  **estructive Inspection (NDT Inspection) of the ailerons control**  **rod fitting lugs for cracks. Reference No.:**  **AOT-CN235-57-0001**

**Revision No.: 1**  **Date**

**: 14/03/2014**  

# Alert Operators Transmission **Page 2/11** 
ATA Chapter: **57**
Subject: **Inspection of Aileron Control Rod Fittings**



### 3. SHORT TERM ACTION

**3.1 PLANNING AND MANPOWER** 

**3.1.1 ACCOMPLISHMENT TIMESCALE** 

**The inspection described in annex I has to be perfo rmed on all CN-235 aircraft with more than 10 years**  **or 8000 FH since the first flight, whichever occurs first, at**  **the next scheduled maintenance inspection.**

**3.1.2 MANPOWER** 

**The estimated time to get access and perform the In spection is 30 men hours per aircraft.** 

**3.2 DESCRIPTION** 

**3.2.1 ACCESS** 

**Inspection must be performed with the aileron remov ed from the aircraft in accordance with Ref.3.** 

**3.2.2 INSPECTION REQUIREMENTS** 

**Refer to annex 1 for the complete instructions to a ccomplish the NDT inspection.** 

**3.2.3 FINDINGS** 

**In case of a cracked lug of the control rod fitting s is identified, before next flight contact Airbus**  **Military with a detailed damage report to get further instructions.** 

**3.3 SPARES AND TOOLING** 

**Refer to annex 1 for inspection equipment.**



### 4. FURTHER INFORMATION

**4.1 FOLLOW-UP PLAN** 

**Further actions may be considered based upon result s of the ongoing investigations.** 

**4.2 IMPACTED DOCUMENTATION** 

**Not applicable. Reference No.:**  **AOT-CN235-57-0001**

**Revision No.: 1**  **Date**

**: 14/03/2014**  

# Alert Operators Transmission **Page 3/11** 
ATA Chapter: **57**
Subject: **Inspection of Aileron Control Rod Fittings**



### 5. REPORTING **Questions about this AOT and inspection results wit h or without findings are to be sent to Airbus Mili**  **tary Technical**
**Assistance Center (AMTAC): Telephone: (+34) 91 600 79 99**  **E-mail: MTA.TechnicalService@military.airbus.com**

Released by

Yannick Ville

**© EADS CASA.2013. All rights reserved. Confidential and proprietary document.** 
**This document and all information contained herein is the sole property of EADS CASA.**  **No intellectual property rights are granted by the delivery of this document or the disclosure of its**  **content. This document shall not be reproduced or d isclosed to a third party without the**  **express written consent of EADS CASA.**
**This document and its content shall not be used for any purpose other than that for which it is suppli**  **ed.**

**©EADS CASA 2013 All right reserved Reference No.:**  **AOT-CN235-57-0001**

**Revision No.: 1**  **Date**

**: 14/03/2014**  

# Alert Operators Transmission **Page 4/11** 
ATA Chapter: **57**
Subject: **Inspection of Aileron Control Rod Fittings**



### ANNEX 1 – NDT INSPECTION

1 COMPONENT OR AREA TO BE INSPECTED (refer to Figur e 1)

**A. The hinge fittings of the aileron attachment to the outer wing at stations Y=8110, Y=9910 and Y=117**  **50 and the actuator attachment fittings at Y=8110 and Y=9910. LH and RH** 

**.**

**B. At station Y=8110 the wingbox side hinge fitting , the aileron side hinge fitting and the actuator f**  **ittings are to be inspected. Inspection areas are both surfaces of ea**  **ch lug around the lug bushings.**

**C. At station Y=9910 the intermediate linkage part, the aileron side hinge fitting and the actuator fi**  **ttings will be inspected. Inspection areas are both surfaces of each lug arou**  **nd the bushings and the upper and lower fillet radi i of the intermediate**  **linkage part.**

**D. At station Y=11750 the intermediate linkage part and the aileron side hinge fitting will be inspect**  **ed. Inspection areas are both surfaces of each lug around the bushings and t**  **he upper and lower fillet radii of the intermediate linkage part.** 

2 DESCRIPTIONOF POSSIBLE DAMAGE (refer to Figure 2)

**A. Fatigue cracks emanating from the inner diameter of the lug extending radially. Cracks will be dete**  **ctable when equal or greater than 2 mm (0.079 in) from the bushing edge.** 

**B. Fatigue cracks equal or greater than 2 mm (0.079 in.) starting at the edge of the fillet radius and**  **propagating along the radius and across the section of the fitting base.** 

3 EQUIPMENT AND MATERIALS

**A. Any equivalent eddy current equipment with scope display/probe combination which satisfies the requ**  **irements of this procedure may be used.** 

**B. The equipment used in the development of this pr ocedure was as follows:** 

**1. Instrument: NORTEC 2000 from OLYMPUS. 2. Probes: Absolute shielded probe PAB-90C401 (**  **cranked probe),**

**1 MHz with probe tip diameter 0,125 in., micro dot connector from EC NDT**  **Absolute shielded extra-flat probe MP.060-60BL , 50-500kHz from Olympus** 

**NOTE: Flat probe not needed if aileron is remo ved.**  **3. Cable: EC-N2K-TL-6 (Lemo 0 triaxial to Lemo 16p) from EC NDT**  **4. Calibration Standard: 2-164-551, NFe from Ins titut Dr. Foerster (shown in Figure 3)** **Reference No.: AOT-CN235-57-0001** 

**Revision No.: 1**  **Date**

**: 14/03/2014**  

# Alert Operators Transmission **Page 5/11** 
ATA Chapter: **57**
Subject: **Inspection of Aileron Control Rod Fittings**

4 PREPARATION FOR INSPECTION

**WARNING : MAKE SURE THAT ALL SAFETY PROCEDURES ARE FOLLOWED**  **TO PREVENT INJURY TO PERSON**

**OR DAMAGE TO THE AIRCRAFT. ENSURE THAT NECESSARY W ARNING NOTICES ARE IN POSITION BEFORE** 

**YOU START THE TASK.**

**A. It might be necessary to remove the aileron comp letely to get proper access to the inspection areas** 

**.**

**B. Ensure that there is no sealant on the inspectio n area.** 

**C. Ensure that paint coating thickness does not exc ess 350 μm.** 

**(1) If the paint thickness is greater than 350 μm, the inspection cannot be done. The paint must be s**  **tripped or reduced in thickness to less than 350μm.** 

**(2) If the paint thickness is less than 350 μm, a plastic foils corresponding to the paint thickness**  **(±30 μm), must be placed on the surface of the calibration sta**  **ndard during calibration steps.**

**D. Make sure that the surface of the inspection are a is clean and smooth.** 

**NOTE: The area to be inspected (refer to Figure 1) has to be visually checked for discontinuities suc**  **h as bulging, dents, peeled paint, visible corrosion or any othe**  **r condition that may affect accuracy of the eddy cu rrent**  **inspection.**

5 INSTRUMENT CALIBRATION (refer to Figure 4)

**A. Set the instrument test parameters as indicated below:** 

**Frequency: 1 MHz/ 500kHz, depending on the probe.**

**H-Pos: 70**

**V-Pos: 20**
**Probe drive: Medium**

**B. Use calibration standard 2.164-551 to calibrate the instrument in accordance with the manufacturer’**  **s instructions.**

**C. Position the probe on a slot-free area and press Null to adjust the zero of the instrument.** 

**D. Alternatively place and move the probe away from the calibration standard while adjusting phase ang**  **le to get a horizontal lift-off response equivalent to that sho**  **wn in Figure 4.**

**E. Move the probe across the 0,5 mm slot in the cal ibration standard and adjust the instrument sensiti**  **vity (gain) to get a signal amplitude of 50% FSH and similar shape as th**  **at shown in Figure 4.**

**F. Move the probe across the 0,2 mm slot in the cal ibration standard and confirm that the indication o**  **n the screen is greater than 10% of the screen height.** **Reference No.: AOT-CN235-57-0001** 

**Revision No.: 1**  **Date**

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# Alert Operators Transmission **Page 6/11** 
ATA Chapter: **57**
Subject: **Inspection of Aileron Control Rod Fittings**

6 INSPECTION PROCEDURE (refer to Figure 5)

**A. Place the selected probe on the fitting surface (compensation point) and press Null to adjust the z**  **ero of the instrument in**
**the screen.**

**NOTE: One compensation point will be selected for each fitting and for each different area: for the l**  **ug it will be close the bushing and for the fillet radius and cr**  **oss section will be the fitting surface.**

**B. Alternatively place and move the probe away from the compensation point while adjusting the phase a**  **ngle to get a horizontal lift-off response. Do not modify any oth**  **er of the parameters got during calibration.**

**C. Slide the probe on both surfaces of each lug as close as possible to the fitting bushing.** 

**D. Slide the probe across the fillet radius using t he scanning movements indicated in Figure 5.** 

**E. Inspect the fillet radius section by sliding the probe as close as possible to the fitting base edg**  **e.**

**E. Any screen indication similar to that shown in F igure 4 greater than 10% FSH not caused by the bush**  **ing edge effect or any other geometrical effect shall be considered as**  **a crack.**

**F. Record position of any crack indication.**

**G. Evaluate the length of any crack scanning from t he point of maximum amplitude towards its side in p**  **arallel scanning paths with 1 mm index up to the point where the amp**  **litude reduces to 10% FSH.**

7 ACCEPTANCE CRITERIA

**All indication which cause screen deflection equal or greater than 10% FSH above the zero point simila**  **r to that shown in Figure 4 not caused by edge effect, the effect of t**  **he bushing or any other geometrical effect shall be considered as a crack** 
**and must be recorded**

8 FINAL NDT REQUIREMENTS

**None. Reference No.:**  **AOT-CN235-57-0001**

**Revision No.: 1**  **Date**

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ATA Chapter: **57**
Subject: **Inspection of Aileron Control Rod Fittings Reference No.:**  **AOT-CN235-57-0001**

**Revision No.: 1**  **Date**

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# Alert Operators Transmission **Page 8/11** 
ATA Chapter: **57**
Subject: **Inspection of Aileron Control Rod Fittings Reference No.:**  **AOT-CN235-57-0001**

**Revision No.: 1**  **Date**

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# Alert Operators Transmission **Page 9/11** 
ATA Chapter: **57**
Subject: **Inspection of Aileron Control Rod Fittings Reference No.:**  **AOT-CN235-57-0001**

**Revision No.: 1**  **Date**

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# Alert Operators Transmission **Page 10/11** 
ATA Chapter: **57**
Subject: **Inspection of Aileron Control Rod Fittings Reference No.:**  **AOT-CN235-57-0001**

**Revision No.: 1**  **Date**

**: 14/03/2014**  

# Alert Operators Transmission **Page 11/11** 
ATA Chapter: **57**
Subject: **Inspection of Aileron Control Rod Fittings**