Agencies: Past Incidents Underscore Need For Inspections

As regular Aero-News readers know, there have been as many as seven incidents reported where the nosewheels on Airbus A320-series airlines have become jammed at a 90-degree angle, leading to some rather spectacular landings -- televised, or not.

It is both amazing, and also not so much, that none of these incidents has led to any injuries (excepting, of course, the nosewheel assemblies of the affected jets.) Amazing, because in each of these examples the pilots brought their wounded aircraft in for relatively routine (albeit theatrically brilliant) landings. Some sparks, burned rubber, and melted magnesium -- that's pretty much it.

The reason such feats aren't amazing, is because they're exactly why commercial airline pilots train as long, as intensively, and as expensively as they do: for that one time in a million when such scenarios are no longer academic exercises, but instead real-life situations. Each of those cases was an example of expert communication, professional piloting, and old-fashioned by-the-book problem-solving skill. Monday's televised drama in Hillsboro involving a Nike Corporation Gulfstream V was another example of this.

Still, clearly there is some kind of issue with the A320s nose landing gear (NLG) assembly -- or more specifically, with a specific component of it. In response, the FAA and the Australian Civil Aviation Safety Authority (CASA) both issued Airworthiness Directives Wednesday for the A320, both for the same component.

Each AD requires operators to check the NLG upper support arms on all A318, A319, A320, and A321 airplanes. According to the agencies, these arms may have been improperly connected after installation of a certain type of braking and steering control unit -- which could result in yet another spark-filled landing down the line.

Aero-News presents these airworthiness directives -- as we do with all AD's -- both as a service to our readers in the affected areas of the aviation community, as well as to educate those interested in how such procedures are identified and implemented.

Just because you fly a Skyhawk, and not an airliner, doesn't necessarily mean you can't learn something...

AD: Airbus

AD NUMBER: 2005-24-06
MANUFACTURER: Airbus
SUBJECT: Airworthiness Directive 2005-24-06
SUMMARY: The FAA is adopting a new airworthiness directive (AD) for all Airbus Model A318-100, A319-100,A320-200, A321-100, and A321-200 series airplanes, and Model A320-111 airplanes. This AD requires an inspection to determine whether certain braking and steering control units (BSCUs) are installed or have ever been installed. For airplanes on which certain BSCUs are installed or have ever been installed, this AD requires an inspection of the nose landing gear (NLG) upper support and corrective action if necessary, and a check of the NLG strut inflation pressure and an adjustment if necessary. For some of these airplanes, this AD also requires a revision to the aircraft flight manual to incorporate an operating procedure to recover normal steering in the event of a steering failure. This AD results from a report of an incident where an airplane landed with the NLG turned 90 degrees from centerline. We are issuing this AD to prevent landings with the NLG turned 90 degrees from centerline, which could result in reduced controllability of the airplane.

Urgent CASA AD: Airbus

Applicability: AIRBUS A318, A319, A320 and A321 aircraft that are equipped with a Braking and Steering Control Unit (BSCU) part number (PN) E21327001 (Standard L4.1,
AIRBUS Modification 26965 - Service Bulletin A320-32-1912) or PN E21327003
(Standard L4.5, AIRBUS Modification 33376 - Service Bulletin A320-32-1261).

This Airworthiness Directive (AD) is not applicable to aircraft that have been delivered and equipped with BSCU standard L4.8 from production incorporating modification 35216.

Requirement: 1. The following operational procedure is only for those aircraft that have not incorporated AIRBUS modification 31152 in production (i.e. applicable only to aircraft with the steering powered by the green hydraulic system).
Incorporate the following into in the Aircraft Operations Manual, or AFM TR 4.02.00/33 for aircraft without FWC H2E3P or H1E3P or subsequent standard, or TR 4.02.00/34 for aircraft with FWC H2E3P or H1E3P.
The ECAM message, in case of a nose wheel steering failure, will be worded as follows:
- “WHEEL N/W STRG FAULT” for aircraft with FWC software post E3P
- “WHEEL N.W STEER FAULT” for aircraft with FWC software pre E3P

If the L/G SHOCK ABSORBER FAULT ECAM caution is triggered at any time in flight, and the WHEEL N/W STRG FAULT ECAM caution is triggered after the landing gear extension:

• When all landing gear doors are indicated closed on ECAMWHEEL page, reset the BSCU:
- A/SKID&N/W STRG---------------------------OFF THEN ON
• If the WHEEL N/W STRG FAULT ECAM caution is no longer displayed, this indicates a successful nose wheel re-centering and steering recovery.
- Rearm the AUTO BRAKE, if necessary.
• If the WHEEL N/W STRG FAULT ECAM caution remains displayed, this indicates that the nose wheel steering remains lost, and that the nose wheels are not centered.
- During landing, delay nose wheel touchdown for as long as possible.
- Refer to the ECAM STATUS
If the WHEEL N/W STRG FAULT ECAM caution appears, without the L/G SHOCK ABSORBER FAULT ECAM caution:
- No specific crew action is requested by the WHEEL N/M STRG FAULT ECAM caution procedure.
- Refer to the ECAM STATUS

2. Check the NLG strut inflation pressure, weight off and weight on wheels, in accordance with AIRBUS Aircraft Maintenance Manual (AMM) 12-14-32 and its associated TR issued on 13 November 2005; and perform a one time boroscopic inspection of the NLG upper support (backplate) to detect anti-rotation lugs ruptured (completely broken), in accordance with AIRBUS Technical Note 957.1901/05, dated 18 October 2005; and Report the results of all inspections to AIRBUS.
3. If any upper support anti-rotation lugs are found ruptured (completely broken), carry out all necessary actions to get a serviceable NLG (contact AIRBUS Fax: 33 5 61 93 32 73).
Note: DGAC AD F-2005-191 EASA reference No 2005-6411 dated 15 November 2005 refers.

Compliance: 1. From the effective date of this AD.

2. Within 100 flight cycles following an ECAM caution ‘L/G SHOCK ABSORBER FAULT’ associated with at least one of the following Centralised Fault Display System (CFDS) messages:

‘N L/G EXT PROX SNSR 24GA TGT POS’,
‘N L/G EXT PROX SNSR 25GA TGT POS’,
‘N L/G SHOCK ABSORBER FAULT 2526GM’.

3. Before further flight

This Airworthiness Directive becomes effective on 5 December 2005.

Background: An event where an A320 landed with the Nose Landing Gear (NLG) wheels rotated at 90 degrees to the aircraft centreline was recently reported. Investigation showed that the upper support of the NLG shock absorber was damaged and the anti- rotation lugs were ruptured. This led the nose wheels to lose their centered position reference normally ensured by the shock-absorber cams. The BSCU had logged a steering system fault, because hydraulic power was not available at the time of steering system checks, therefore the BSCU was not able to proceed with the re-centering of the wheels.

To prevent reoccurrence of landings with the NLG turned 90 degrees, this AD introduces operational procedures and maintenance actions.

FMI: www.faa.gov/regulations_policies/airworthiness_directives/, www.casa.gov.au