Flap System Runaway

TASK 27-51-00-810-820-A
Flap System Runaway

1. Possible Causes

FPPU-FLAP [27CV]
FLAP-PCU [6201CM]

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 27-50-00-480-802	Installation/Removal of the Check Pin at Track 1
AMM 27-50-00-866-012	Manual Retraction of the Flaps
AMM 27-50-00-869-006	Reset of the Wing Tip Brake (WTB) of the Flap System on the Ground
AMM 27-51-00-820-001	Manual Adjustment of the Position Pick-Off Units
AMM 27-51-19-000-001	Removal of the Feed Back Position Pick-Off Unit
AMM 27-51-19-400-001	Installation of the Feed Back Position Pick-Off Unit
AMM 27-54-00-200-001	Detailed Visual Inspection of the Transmission Assembly
AMM 27-54-00-710-001	Operational Test of the Flap System
AMM 27-54-51-000-001	Removal of the Power Control Unit of the Flap System
AMM 27-54-51-400-001	Installation of the Power Control Unit of the Flap System

3. Fault Confirmation
Subtask 27-51-00-730-051-A

A. Analysis

NOTE: 'Runaway' is a position difference between the two APPU's and the FPPU.

(1) Get access to the MENU MODE and set it to SFCC 1 or SFCC 2.
(a) Go to the submenu SYSTEM DATA FLAP.
(b) Press the line key 1L to set the PPU page.

NOTE: The SFCC transmits the LH and RH APPU and the FPPU data page(s) to the CFDS. Every 5 seconds the data of the APPU DATA page(s) will be refreshed.

(c) In the TSM:
Refer to page block 301 TABLE 2 and TABLE 3. The LH APPU, the FPPU and RH APPU synchro angles are shown as a decimal value.

NOTE: A difference of more than 5.2 degrees generates a runaway fault message.

(d) If there is this difference between the LH APPU, the FPPU and RH APPU, do the fault isolation.

4. Fault Isolation
Subtask 27-51-00-810-070-A

A. Procedure
(1) Do the reset of the wing tip brakes AMM 27-50-00-869-006.
(2) Do the detailed inspection of the PCU AMM 27-54-00-200-001.
(3) If no fault is found, do a check of the FPPU zero datum mark AMM 27-51-00-820-001.
(a) If the zero datum mark is not aligned, remove the FPPU AMM 27-51-19-000-001,

visually inspect the PCU mounting interface,
visually inspect the Flap FPPU for signs of water thru the sight glass and the input shaft for visible dent.

(b) If the FPPU is found in good condition, do the steps that follow:
1 With the FPPU not installed on the defective wing:

Do the manual retraction of the flaps on the left and right wing AMM 27-50-00-866-012 until you can install the check pin at each track 1 AMM 27-50-00-480-802.

NOTE: In this condition it is not necessary to record the PPU values before manual extension.

2 Do the manual adjustment of the FPPU AMM 27-51-00-820-001.

If you feel frictions while turning the FPPU input shaft, replace the FPPU-FLAP [27CV] AMM 27-51-19-400-001.
If you feel no friction, install the old FPPU AMM 27-51-19-400-001 again.

(4) Before the operational test:

Put the flap system back to the initial condition AMM 27-50-00-866-012.

(a) Do the operational test of the flap system, AMM 27-54-00-710-001.
(5) If the fault continues, replace the FLAP-PCU [6201CM] , AMM 27-54-51-000-001 and AMM 27-54-51-400-001.
(6) Get access to the FLP ON GROUND FAULTS and make sure check that there are no faults.

5. Close-up
Subtask 27-51-00-860-082-A

A. Put the aircraft back to its initial configuration.

[Rev.8 from Aug 2018] 2026.04.04 04:27:38 UTC