AOL 235-025

Services REV: 00 PAGE: 1 OF 5

Engineering Support DATE: July 29th, 2013

ALL OPERATOR LETTER

This AOL intention is to advise Operators of matters, which might involve safety issues.

Operators may consider, under their own criteria, the actions to be taken.

SUBJECT: BOOSTER PUMP WIRING – DAMAGE

1. BACKGROUND

The CN-235 aircraft is fitted with two booster pumps located inside each side of the center wing and 

accessible from the outside of the wing lower skin (see Figure 1). They are mainly aimed to provide 

fuel to the collector tank (one in each main tank) through jet-pumps located in auxiliary tanks.

The CN-235 aircraft was initially equipped with booster pump P/N RR54630B (Lear Siegler) and, 

from aircraft S/N 059 and onwards with booster pump P/N 1C12-34 and P/N 1C12-46 (Parker).

Airbus Military has been recently informed about an in service event involving one fuel booster pump

P/N 1C12-34. According to the information received, and further to a problem reported in flight 

regarding fuel transfer system, the inspection of one booster pump revealed damages on the 

electrical feeding cable and some burn marks on the pump body and plate (fairing) at the external 

side of the fuel tank (see figure 2).

With the information available to date, the analysis performed by Airbus Military indicates that the 

issue is potentially affecting only to booster pumps P/N 1C12-34 and P/N 1C12-46 (Parker). This 

pump has a restoration interval established of 4.800 FH and no other similar event has been reported 

so far to Airbus Military.

2. PURPOSE

This AOL is issued to inform all CN-235 operators of this event and provide recommendations to 

perform inspections on those CN-235 aircraft fitted with booster pumps P/N 1C12-34 or P/N 1C12-

46.

3. RECOMMENDATION

The following recommendations are aimed to gather in-service aircraft current status of the subject

booster pump feeding cable in support of the investigation of this event that is being performed by 

Airbus Military in close cooperation with the booster pump manufacturer.

Airbus Military recommends to perform a visual inspection of the booster pumps (P/N 1C12-34 or

P/N 1C12-46) feeding cables following the procedure described below and in accordance with the 

following timeframe:

For aircraft accumulating at the time of reception of this AOL 300FH or more since last booster 

pump replacement; perform the inspection of the subject pump before 5 FC after reception of 

this AOL.
AOL 235-025

Services REV: 00 PAGE: 2 OF 5

Engineering Support DATE: July 29th, 2013

SUBJECT: BOOSTER PUMP WIRING – DAMAGE

For aircraft accumulating at the time of reception of this AOL less than 300FH since last booster 

pump replacement; perform the inspection of the subject pump at next “A” check.

3.1.Inspection (Refer to Figure 1)

Preparation for the inspection

Refer to AMM 28-18-00-001 paragraph 4 and perform points C.1.a and C.1.b.

Refer to AMM 28-22-11 (Removal/Installation of the Booster Pump) and perform points C.(2)(a), 

C.(2)(b), C.(2)(c) and C.(2)(f) to get access to the booster pump feeder cable.

Inspection

- Do a visual inspection of the booster pump feeder cable for:

- General condition

- Correct fastening and restraints

- Bonding jumpers correctly installed

- Signs of overheating

- Marks for rubbing or electrical arcing

- Connections in bad condition and legibility of signs

In case of any findings or fuel leaks are detected, report to Airbus Military and replace the booster 

pump before further flight; or within 10 consecutive calendar days, if the following conditions are 

accomplished:

- The affected booster pump must not be used.

- A label “INOP” is placed in corresponding PUMPS button located in Fuel System panel.

- The remaining booster pump must be operative.

- Crossfeed and gravity transfer valves operate normally.

- Both fuel quantity indicators operate normally.

- Low fuel pressure warning system operates normally.

or

- The affected booster pump must not be used.

- A label “INOP” is placed in corresponding PUMPS button located in Fuel System panel.

- The remaining booster pump must be operative.

- Crossfeed valve operates normally.

- Auxiliary fuel tanks remain empty.
AOL 235-025

Services REV: 00 PAGE: 3 OF 5

Engineering Support DATE: July 29th, 2013

SUBJECT: BOOSTER PUMP WIRING – DAMAGE

Close up

Refer to AMM 28-22-11 (Removal/Installation of the Booster Pump) and perform points C.(4)(f), 

C.(4)(g), C.(4)(h), C.(4)(k) and C.(4)(l).

Remove the service platforms

Remove warning notices

Reporting

Please, report inspections results to Airbus Military indicating:

Aircraft MSN, Flight Hours and Flight Cycles

Booster Pump Flight Hours since new and since last restoration

Booster Pump Part Number and Serial Number

Description of findings (or no findings) including pictures.

4. FOLLOW UP

Based on operators collected data, Airbus Military in collaboration with Parker will perform an 

investigation about damage root cause and will provide further recommendations if needed.

For any doubt associated to this All Operator Letter, please contact:

AIRBUS MILITARY

Services / Engineering Support

e-mail: MTA.TechnicalService@military.airbus.com

Fax: +34 91 585 3127

For US operators, additionally contact:

e-mail: TechnicalSupport@airbusmilitaryna.com

Félix Delgado Martínez

HO Engineering Support

Airbus Military / EADS-CASA
AOL 235-025

Services REV: 00 PAGE: 4 OF 5

Engineering Support DATE: July 29th, 2013

SUBJECT: BOOSTER PUMP WIRING – DAMAGE

Figure 1
AOL 235-025

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Engineering Support DATE: July 29th, 2013

SUBJECT: BOOSTER PUMP WIRING – DAMAGE

Figure 2 (Potential Damage).