What makes the Fiesta interesting from a collision repair point of view is that it has been referred to as a "study in high-strength steel," which makes up more than half of its structure. For example, the front and rear rails are 600 MPa dual-phase steel. The rocker panel reinforcements are 780 MPa dual-phase steel (see Figure 2). Both the A- and B-pillar reinforcements and the inner B-pillar are boron-alloyed steel, some of the strongest steel to date available on vehicles.

Repair Possibilities

Figure 2 - The rocker panel reinforcements on the Fiesta are dual-phase 780 steel.Repair possibilities, at least for the rails and the strong reinforcements, are few. But there are some other repairs available. There are bolt-on crush boxes on the ends of both the front and rear rails (see Figures 3 and 4). The crush boxes, as the name implies, are designed to crush in order to absorb collision energy. The crush boxes are not straightened, but easily replaced by bolting on a replacement. More severe collisions that travel rearward of the front crush box or forward of the rear crush box require full replacement of the rail. Due to the DP-600 material, crush zones, and inner reinforcements, a sectioning procedure for the front or rear rails is not available. Only a minor sway in the rails can be straightened.

The boron-alloyed steel A- and B-pillar reinforcements must also be replaced at factory seams, which is typical. The factory workshop (body repair) manual, section 501-35, shows several Figures 3 - The Fiesta features bolt-on crush boxes as extensions on both the front and rear rails. (Front)sectioning possibilities for the mild steel outer side panels. The outer is available as two replacement service parts, cut just behind the B-pillar. Designated sectioning cut lines are shown in the upper A-pillar, forward of the B-pillar in both the roof rail and rocker panel, and in the quarter panel area. Ford has always preferred a butt joint with backing on outer panel seams, preferably using a portion of the existing or replacement panel as a backing.

Other New Features

The Fiesta has seven airbags, including a driver knee airbag. For a mini-car, seven airbags is considered to be many.

The Fiesta is one of the first Ford vehicles with side airbag pressure-based sensors. These sensors measure the steep and quick increase of pressure within the door cavity in the event of a side Figures 4 - The Fiesta features bolt-on crush boxes as extensions on both the front and rear rails. (Rear)impact to trigger the side airbag deployment. The sensors do not rely on an airtight seal in the door cavity, as there are air openings in several places in a door shell. The sensors respond to a quick collapsing of the door shell, indicating a side collision. These sensors have up to 30% faster response time than conventional acceleration-based, side-impact sensors. Other side-impact sensors are still required, in the base of the B-pillars, in case the side collision does not impact the front door.

The 2011 Fiesta also features Ford's new blind-spot mirror, which is a secondary convex spotter in the top outer corner of the door mirrors, aimed directly at the driver's blind spot (see Figure 5). When traffic enters the driver's blind spot on either side of the vehicle, it is visible in the secondary convex mirror.

ConclusionFigure 5 - The small mirror in the corner of the mirror serves as a view of the blind spot.

The 2011 Ford Fiesta, a rebirth of an old model name for Ford, features several applications of high-strength and ultra-high-strength steel. Front and rear bolt-on crush boxes make them easy to replace in minor frontal collisions. There are several sectioning possibilities for the outer side panels. The Ford Fiesta features seven airbags, pressure-based side airbag sensors, and a new type of blind spot mirror.

This article first appeared in the December 17, 2010 edition of the I-CAR Advantage Online.

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